5v62

Structural highlights

Function

[MK01_HUMAN] Serine/threonine kinase which acts as an essential component of the MAP kinase signal transduction pathway. MAPK1/ERK2 and MAPK3/ERK1 are the 2 MAPKs which play an important role in the MAPK/ERK cascade. They participate also in a signaling cascade initiated by activated KIT and KITLG/SCF. Depending on the cellular context, the MAPK/ERK cascade mediates diverse biological functions such as cell growth, adhesion, survival and differentiation through the regulation of transcription, translation, cytoskeletal rearrangements. The MAPK/ERK cascade plays also a role in initiation and regulation of meiosis, mitosis, and postmitotic functions in differentiated cells by phosphorylating a number of transcription factors. About 160 substrates have already been discovered for ERKs. Many of these substrates are localized in the nucleus, and seem to participate in the regulation of transcription upon stimulation. However, other substrates are found in the cytosol as well as in other cellular organelles, and those are responsible for processes such as translation, mitosis and apoptosis. Moreover, the MAPK/ERK cascade is also involved in the regulation of the endosomal dynamics, including lysosome processing and endosome cycling through the perinuclear recycling compartment (PNRC); as well as in the fragmentation of the Golgi apparatus during mitosis. The substrates include transcription factors (such as ATF2, BCL6, ELK1, ERF, FOS, HSF4 or SPZ1), cytoskeletal elements (such as CANX, CTTN, GJA1, MAP2, MAPT, PXN, SORBS3 or STMN1), regulators of apoptosis (such as BAD, BTG2, CASP9, DAPK1, IER3, MCL1 or PPARG), regulators of translation (such as EIF4EBP1) and a variety of other signaling-related molecules (like ARHGEF2, DCC, FRS2 or GRB10). Protein kinases (such as RAF1, RPS6KA1/RSK1, RPS6KA3/RSK2, RPS6KA2/RSK3, RPS6KA6/RSK4, SYK, MKNK1/MNK1, MKNK2/MNK2, RPS6KA5/MSK1, RPS6KA4/MSK2, MAPKAPK3 or MAPKAPK5) and phosphatases (such as DUSP1, DUSP4, DUSP6 or DUSP16) are other substrates which enable the propagation the MAPK/ERK signal to additional cytosolic and nuclear targets, thereby extending the specificity of the cascade. May play a role in the spindle assembly checkpoint.^{[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23]} Acts as a transcriptional repressor. Binds to a [GC]AAA[GC] consensus sequence. Repress the expression of interferon gamma-induced genes. Seems to bind to the promoter of CCL5, DMP1, IFIH1, IFITM1, IRF7, IRF9, LAMP3, OAS1, OAS2, OAS3 and STAT1. Transcriptional activity is independent of kinase activity.^{[24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45] [46]} [KS6A1_HUMAN] Serine/threonine-protein kinase that acts downstream of ERK (MAPK1/ERK2 and MAPK3/ERK1) signaling and mediates mitogenic and stress-induced activation of the transcription factors CREB1, ETV1/ER81 and NR4A1/NUR77, regulates translation through RPS6 and EIF4B phosphorylation, and mediates cellular proliferation, survival, and differentiation by modulating mTOR signaling and repressing pro-apoptotic function of BAD and DAPK1. In fibroblast, is required for EGF-stimulated phosphorylation of CREB1, which results in the subsequent transcriptional activation of several immediate-early genes. In response to mitogenic stimulation (EGF and PMA), phosphorylates and activates NR4A1/NUR77 and ETV1/ER81 transcription factors and the cofactor CREBBP. Upon insulin-derived signal, acts indirectly on the transcription regulation of several genes by phosphorylating GSK3B at 'Ser-9' and inhibiting its activity. Phosphorylates RPS6 in response to serum or EGF via an mTOR-independent mechanism and promotes translation initiation by facilitating assembly of the preinitiation complex. In response to insulin, phosphorylates EIF4B, enhancing EIF4B affinity for the EIF3 complex and stimulating cap-dependent translation. Is involved in the mTOR nutrient-sensing pathway by directly phosphorylating TSC2 at 'Ser-1798', which potently inhibits TSC2 ability to suppress mTOR signaling, and mediates phosphorylation of RPTOR, which regulates mTORC1 activity and may promote rapamycin-sensitive signaling independently of the PI3K/AKT pathway. Mediates cell survival by phosphorylating the pro-apoptotic proteins BAD and DAPK1 and suppressing their pro-apoptotic function. Promotes the survival of hepatic stellate cells by phosphorylating CEBPB in response to the hepatotoxin carbon tetrachloride (CCl4). Is involved in cell cycle regulation by phosphorylating the CDK inhibitor CDKN1B, which promotes CDKN1B association with 14-3-3 proteins and prevents its translocation to the nucleus and inhibition of G1 progression.^{[47] [48] [49] [50] [51] [52] [53] [54] [55] [56] [57]}

References

1. ↑ Sgouras DN, Athanasiou MA, Beal GJ Jr, Fisher RJ, Blair DG, Mavrothalassitis GJ. ERF: an ETS domain protein with strong transcriptional repressor activity, can suppress ets-associated tumorigenesis and is regulated by phosphorylation during cell cycle and mitogenic stimulation. EMBO J. 1995 Oct 2;14(19):4781-93. PMID:7588608
2. ↑ Sithanandam G, Latif F, Duh FM, Bernal R, Smola U, Li H, Kuzmin I, Wixler V, Geil L, Shrestha S. 3pK, a new mitogen-activated protein kinase-activated protein kinase located in the small cell lung cancer tumor suppressor gene region. Mol Cell Biol. 1996 Mar;16(3):868-76. PMID:8622688
3. ↑ Ni H, Wang XS, Diener K, Yao Z. MAPKAPK5, a novel mitogen-activated protein kinase (MAPK)-activated protein kinase, is a substrate of the extracellular-regulated kinase (ERK) and p38 kinase. Biochem Biophys Res Commun. 1998 Feb 13;243(2):492-6. PMID:9480836 doi:S0006-291X(98)98135-9
4. ↑ Deak M, Clifton AD, Lucocq LM, Alessi DR. Mitogen- and stress-activated protein kinase-1 (MSK1) is directly activated by MAPK and SAPK2/p38, and may mediate activation of CREB. EMBO J. 1998 Aug 3;17(15):4426-41. PMID:9687510 doi:10.1093/emboj/17.15.4426
5. ↑ Niu H, Ye BH, Dalla-Favera R. Antigen receptor signaling induces MAP kinase-mediated phosphorylation and degradation of the BCL-6 transcription factor. Genes Dev. 1998 Jul 1;12(13):1953-61. PMID:9649500
6. ↑ Camps M, Nichols A, Gillieron C, Antonsson B, Muda M, Chabert C, Boschert U, Arkinstall S. Catalytic activation of the phosphatase MKP-3 by ERK2 mitogen-activated protein kinase. Science. 1998 May 22;280(5367):1262-5. PMID:9596579
7. ↑ Cruzalegui FH, Cano E, Treisman R. ERK activation induces phosphorylation of Elk-1 at multiple S/T-P motifs to high stoichiometry. Oncogene. 1999 Dec 23;18(56):7948-57. PMID:10637505 doi:10.1038/sj.onc.1203362
8. ↑ Brondello JM, Pouyssegur J, McKenzie FR. Reduced MAP kinase phosphatase-1 degradation after p42/p44MAPK-dependent phosphorylation. Science. 1999 Dec 24;286(5449):2514-7. PMID:10617468
9. ↑ Scheper GC, Morrice NA, Kleijn M, Proud CG. The mitogen-activated protein kinase signal-integrating kinase Mnk2 is a eukaryotic initiation factor 4E kinase with high levels of basal activity in mammalian cells. Mol Cell Biol. 2001 Feb;21(3):743-54. PMID:11154262 doi:10.1128/MCB.21.3.743-754.2001
10. ↑ Ouwens DM, de Ruiter ND, van der Zon GC, Carter AP, Schouten J, van der Burgt C, Kooistra K, Bos JL, Maassen JA, van Dam H. Growth factors can activate ATF2 via a two-step mechanism: phosphorylation of Thr71 through the Ras-MEK-ERK pathway and of Thr69 through RalGDS-Src-p38. EMBO J. 2002 Jul 15;21(14):3782-93. PMID:12110590 doi:10.1093/emboj/cdf361
11. ↑ Garcia J, Ye Y, Arranz V, Letourneux C, Pezeron G, Porteu F. IEX-1: a new ERK substrate involved in both ERK survival activity and ERK activation. EMBO J. 2002 Oct 1;21(19):5151-63. PMID:12356731
12. ↑ Wu Y, Chen Z, Ullrich A. EGFR and FGFR signaling through FRS2 is subject to negative feedback control by ERK1/2. Biol Chem. 2003 Aug;384(8):1215-26. PMID:12974390 doi:http://dx.doi.org/10.1515/BC.2003.134
13. ↑ Masuda K, Shima H, Katagiri C, Kikuchi K. Activation of ERK induces phosphorylation of MAPK phosphatase-7, a JNK specific phosphatase, at Ser-446. J Biol Chem. 2003 Aug 22;278(34):32448-56. Epub 2003 Jun 6. PMID:12794087 doi:10.1074/jbc.M213254200
14. ↑ Allan LA, Morrice N, Brady S, Magee G, Pathak S, Clarke PR. Inhibition of caspase-9 through phosphorylation at Thr 125 by ERK MAPK. Nat Cell Biol. 2003 Jul;5(7):647-54. PMID:12792650 doi:10.1038/ncb1005
15. ↑ Mitsushima M, Suwa A, Amachi T, Ueda K, Kioka N. Extracellular signal-regulated kinase activated by epidermal growth factor and cell adhesion interacts with and phosphorylates vinexin. J Biol Chem. 2004 Aug 13;279(33):34570-7. Epub 2004 Jun 7. PMID:15184391 doi:10.1074/jbc.M402304200
16. ↑ Domina AM, Vrana JA, Gregory MA, Hann SR, Craig RW. MCL1 is phosphorylated in the PEST region and stabilized upon ERK activation in viable cells, and at additional sites with cytotoxic okadaic acid or taxol. Oncogene. 2004 Jul 8;23(31):5301-15. PMID:15241487 doi:10.1038/sj.onc.1207692
17. ↑ Langlais P, Wang C, Dong LQ, Carroll CA, Weintraub ST, Liu F. Phosphorylation of Grb10 by mitogen-activated protein kinase: identification of Ser150 and Ser476 of human Grb10zeta as major phosphorylation sites. Biochemistry. 2005 Jun 21;44(24):8890-7. PMID:15952796 doi:10.1021/bi050413i
18. ↑ Chen CH, Wang WJ, Kuo JC, Tsai HC, Lin JR, Chang ZF, Chen RH. Bidirectional signals transduced by DAPK-ERK interaction promote the apoptotic effect of DAPK. EMBO J. 2005 Jan 26;24(2):294-304. Epub 2004 Dec 16. PMID:15616583 doi:10.1038/sj.emboj.7600510
19. ↑ Hong JW, Ryu MS, Lim IK. Phosphorylation of serine 147 of tis21/BTG2/pc3 by p-Erk1/2 induces Pin-1 binding in cytoplasm and cell death. J Biol Chem. 2005 Jun 3;280(22):21256-63. Epub 2005 Mar 23. PMID:15788397 doi:10.1074/jbc.M500318200
20. ↑ Dougherty MK, Muller J, Ritt DA, Zhou M, Zhou XZ, Copeland TD, Conrads TP, Veenstra TD, Lu KP, Morrison DK. Regulation of Raf-1 by direct feedback phosphorylation. Mol Cell. 2005 Jan 21;17(2):215-24. PMID:15664191 doi:10.1016/j.molcel.2004.11.055
21. ↑ Hu Y, Mivechi NF. Association and regulation of heat shock transcription factor 4b with both extracellular signal-regulated kinase mitogen-activated protein kinase and dual-specificity tyrosine phosphatase DUSP26. Mol Cell Biol. 2006 Apr;26(8):3282-94. PMID:16581800 doi:26/8/3282
22. ↑ Hu S, Xie Z, Onishi A, Yu X, Jiang L, Lin J, Rho HS, Woodard C, Wang H, Jeong JS, Long S, He X, Wade H, Blackshaw S, Qian J, Zhu H. Profiling the human protein-DNA interactome reveals ERK2 as a transcriptional repressor of interferon signaling. Cell. 2009 Oct 30;139(3):610-22. doi: 10.1016/j.cell.2009.08.037. PMID:19879846 doi:10.1016/j.cell.2009.08.037
23. ↑ Sun J, Pedersen M, Ronnstrand L. The D816V mutation of c-Kit circumvents a requirement for Src family kinases in c-Kit signal transduction. J Biol Chem. 2009 Apr 24;284(17):11039-47. doi: 10.1074/jbc.M808058200. Epub 2009, Mar 5. PMID:19265199 doi:10.1074/jbc.M808058200
24. ↑ Sgouras DN, Athanasiou MA, Beal GJ Jr, Fisher RJ, Blair DG, Mavrothalassitis GJ. ERF: an ETS domain protein with strong transcriptional repressor activity, can suppress ets-associated tumorigenesis and is regulated by phosphorylation during cell cycle and mitogenic stimulation. EMBO J. 1995 Oct 2;14(19):4781-93. PMID:7588608
25. ↑ Sithanandam G, Latif F, Duh FM, Bernal R, Smola U, Li H, Kuzmin I, Wixler V, Geil L, Shrestha S. 3pK, a new mitogen-activated protein kinase-activated protein kinase located in the small cell lung cancer tumor suppressor gene region. Mol Cell Biol. 1996 Mar;16(3):868-76. PMID:8622688
26. ↑ Ni H, Wang XS, Diener K, Yao Z. MAPKAPK5, a novel mitogen-activated protein kinase (MAPK)-activated protein kinase, is a substrate of the extracellular-regulated kinase (ERK) and p38 kinase. Biochem Biophys Res Commun. 1998 Feb 13;243(2):492-6. PMID:9480836 doi:S0006-291X(98)98135-9
27. ↑ Deak M, Clifton AD, Lucocq LM, Alessi DR. Mitogen- and stress-activated protein kinase-1 (MSK1) is directly activated by MAPK and SAPK2/p38, and may mediate activation of CREB. EMBO J. 1998 Aug 3;17(15):4426-41. PMID:9687510 doi:10.1093/emboj/17.15.4426
28. ↑ Niu H, Ye BH, Dalla-Favera R. Antigen receptor signaling induces MAP kinase-mediated phosphorylation and degradation of the BCL-6 transcription factor. Genes Dev. 1998 Jul 1;12(13):1953-61. PMID:9649500
29. ↑ Camps M, Nichols A, Gillieron C, Antonsson B, Muda M, Chabert C, Boschert U, Arkinstall S. Catalytic activation of the phosphatase MKP-3 by ERK2 mitogen-activated protein kinase. Science. 1998 May 22;280(5367):1262-5. PMID:9596579
30. ↑ Cruzalegui FH, Cano E, Treisman R. ERK activation induces phosphorylation of Elk-1 at multiple S/T-P motifs to high stoichiometry. Oncogene. 1999 Dec 23;18(56):7948-57. PMID:10637505 doi:10.1038/sj.onc.1203362
31. ↑ Brondello JM, Pouyssegur J, McKenzie FR. Reduced MAP kinase phosphatase-1 degradation after p42/p44MAPK-dependent phosphorylation. Science. 1999 Dec 24;286(5449):2514-7. PMID:10617468
32. ↑ Scheper GC, Morrice NA, Kleijn M, Proud CG. The mitogen-activated protein kinase signal-integrating kinase Mnk2 is a eukaryotic initiation factor 4E kinase with high levels of basal activity in mammalian cells. Mol Cell Biol. 2001 Feb;21(3):743-54. PMID:11154262 doi:10.1128/MCB.21.3.743-754.2001
33. ↑ Ouwens DM, de Ruiter ND, van der Zon GC, Carter AP, Schouten J, van der Burgt C, Kooistra K, Bos JL, Maassen JA, van Dam H. Growth factors can activate ATF2 via a two-step mechanism: phosphorylation of Thr71 through the Ras-MEK-ERK pathway and of Thr69 through RalGDS-Src-p38. EMBO J. 2002 Jul 15;21(14):3782-93. PMID:12110590 doi:10.1093/emboj/cdf361
34. ↑ Garcia J, Ye Y, Arranz V, Letourneux C, Pezeron G, Porteu F. IEX-1: a new ERK substrate involved in both ERK survival activity and ERK activation. EMBO J. 2002 Oct 1;21(19):5151-63. PMID:12356731
35. ↑ Wu Y, Chen Z, Ullrich A. EGFR and FGFR signaling through FRS2 is subject to negative feedback control by ERK1/2. Biol Chem. 2003 Aug;384(8):1215-26. PMID:12974390 doi:http://dx.doi.org/10.1515/BC.2003.134
36. ↑ Masuda K, Shima H, Katagiri C, Kikuchi K. Activation of ERK induces phosphorylation of MAPK phosphatase-7, a JNK specific phosphatase, at Ser-446. J Biol Chem. 2003 Aug 22;278(34):32448-56. Epub 2003 Jun 6. PMID:12794087 doi:10.1074/jbc.M213254200
37. ↑ Allan LA, Morrice N, Brady S, Magee G, Pathak S, Clarke PR. Inhibition of caspase-9 through phosphorylation at Thr 125 by ERK MAPK. Nat Cell Biol. 2003 Jul;5(7):647-54. PMID:12792650 doi:10.1038/ncb1005
38. ↑ Mitsushima M, Suwa A, Amachi T, Ueda K, Kioka N. Extracellular signal-regulated kinase activated by epidermal growth factor and cell adhesion interacts with and phosphorylates vinexin. J Biol Chem. 2004 Aug 13;279(33):34570-7. Epub 2004 Jun 7. PMID:15184391 doi:10.1074/jbc.M402304200
39. ↑ Domina AM, Vrana JA, Gregory MA, Hann SR, Craig RW. MCL1 is phosphorylated in the PEST region and stabilized upon ERK activation in viable cells, and at additional sites with cytotoxic okadaic acid or taxol. Oncogene. 2004 Jul 8;23(31):5301-15. PMID:15241487 doi:10.1038/sj.onc.1207692
40. ↑ Langlais P, Wang C, Dong LQ, Carroll CA, Weintraub ST, Liu F. Phosphorylation of Grb10 by mitogen-activated protein kinase: identification of Ser150 and Ser476 of human Grb10zeta as major phosphorylation sites. Biochemistry. 2005 Jun 21;44(24):8890-7. PMID:15952796 doi:10.1021/bi050413i
41. ↑ Chen CH, Wang WJ, Kuo JC, Tsai HC, Lin JR, Chang ZF, Chen RH. Bidirectional signals transduced by DAPK-ERK interaction promote the apoptotic effect of DAPK. EMBO J. 2005 Jan 26;24(2):294-304. Epub 2004 Dec 16. PMID:15616583 doi:10.1038/sj.emboj.7600510
42. ↑ Hong JW, Ryu MS, Lim IK. Phosphorylation of serine 147 of tis21/BTG2/pc3 by p-Erk1/2 induces Pin-1 binding in cytoplasm and cell death. J Biol Chem. 2005 Jun 3;280(22):21256-63. Epub 2005 Mar 23. PMID:15788397 doi:10.1074/jbc.M500318200
43. ↑ Dougherty MK, Muller J, Ritt DA, Zhou M, Zhou XZ, Copeland TD, Conrads TP, Veenstra TD, Lu KP, Morrison DK. Regulation of Raf-1 by direct feedback phosphorylation. Mol Cell. 2005 Jan 21;17(2):215-24. PMID:15664191 doi:10.1016/j.molcel.2004.11.055
44. ↑ Hu Y, Mivechi NF. Association and regulation of heat shock transcription factor 4b with both extracellular signal-regulated kinase mitogen-activated protein kinase and dual-specificity tyrosine phosphatase DUSP26. Mol Cell Biol. 2006 Apr;26(8):3282-94. PMID:16581800 doi:26/8/3282
45. ↑ Hu S, Xie Z, Onishi A, Yu X, Jiang L, Lin J, Rho HS, Woodard C, Wang H, Jeong JS, Long S, He X, Wade H, Blackshaw S, Qian J, Zhu H. Profiling the human protein-DNA interactome reveals ERK2 as a transcriptional repressor of interferon signaling. Cell. 2009 Oct 30;139(3):610-22. doi: 10.1016/j.cell.2009.08.037. PMID:19879846 doi:10.1016/j.cell.2009.08.037
46. ↑ Sun J, Pedersen M, Ronnstrand L. The D816V mutation of c-Kit circumvents a requirement for Src family kinases in c-Kit signal transduction. J Biol Chem. 2009 Apr 24;284(17):11039-47. doi: 10.1074/jbc.M808058200. Epub 2009, Mar 5. PMID:19265199 doi:10.1074/jbc.M808058200
47. ↑ Dalby KN, Morrice N, Caudwell FB, Avruch J, Cohen P. Identification of regulatory phosphorylation sites in mitogen-activated protein kinase (MAPK)-activated protein kinase-1a/p90rsk that are inducible by MAPK. J Biol Chem. 1998 Jan 16;273(3):1496-505. PMID:9430688
48. ↑ Shimamura A, Ballif BA, Richards SA, Blenis J. Rsk1 mediates a MEK-MAP kinase cell survival signal. Curr Biol. 2000 Feb 10;10(3):127-35. PMID:10679322
49. ↑ Buck M, Poli V, Hunter T, Chojkier M. C/EBPbeta phosphorylation by RSK creates a functional XEXD caspase inhibitory box critical for cell survival. Mol Cell. 2001 Oct;8(4):807-16. PMID:11684016
50. ↑ Wu J, Janknecht R. Regulation of the ETS transcription factor ER81 by the 90-kDa ribosomal S6 kinase 1 and protein kinase A. J Biol Chem. 2002 Nov 8;277(45):42669-79. Epub 2002 Sep 3. PMID:12213813 doi:10.1074/jbc.M205501200
51. ↑ Hu Y, Fang X, Dunham SM, Prada C, Stachowiak EK, Stachowiak MK. 90-kDa ribosomal S6 kinase is a direct target for the nuclear fibroblast growth factor receptor 1 (FGFR1): role in FGFR1 signaling. J Biol Chem. 2004 Jul 9;279(28):29325-35. Epub 2004 Apr 26. PMID:15117958 doi:10.1074/jbc.M311144200
52. ↑ Roux PP, Ballif BA, Anjum R, Gygi SP, Blenis J. Tumor-promoting phorbol esters and activated Ras inactivate the tuberous sclerosis tumor suppressor complex via p90 ribosomal S6 kinase. Proc Natl Acad Sci U S A. 2004 Sep 14;101(37):13489-94. Epub 2004 Sep 1. PMID:15342917 doi:10.1073/pnas.0405659101
53. ↑ Anjum R, Roux PP, Ballif BA, Gygi SP, Blenis J. The tumor suppressor DAP kinase is a target of RSK-mediated survival signaling. Curr Biol. 2005 Oct 11;15(19):1762-7. PMID:16213824 doi:10.1016/j.cub.2005.08.050
54. ↑ Wingate AD, Campbell DG, Peggie M, Arthur JS. Nur77 is phosphorylated in cells by RSK in response to mitogenic stimulation. Biochem J. 2006 Feb 1;393(Pt 3):715-24. PMID:16223362 doi:10.1042/BJ20050967
55. ↑ Shahbazian D, Roux PP, Mieulet V, Cohen MS, Raught B, Taunton J, Hershey JW, Blenis J, Pende M, Sonenberg N. The mTOR/PI3K and MAPK pathways converge on eIF4B to control its phosphorylation and activity. EMBO J. 2006 Jun 21;25(12):2781-91. Epub 2006 Jun 8. PMID:16763566 doi:10.1038/sj.emboj.7601166
56. ↑ Roux PP, Shahbazian D, Vu H, Holz MK, Cohen MS, Taunton J, Sonenberg N, Blenis J. RAS/ERK signaling promotes site-specific ribosomal protein S6 phosphorylation via RSK and stimulates cap-dependent translation. J Biol Chem. 2007 May 11;282(19):14056-64. Epub 2007 Mar 14. PMID:17360704 doi:10.1074/jbc.M700906200
57. ↑ Carriere A, Cargnello M, Julien LA, Gao H, Bonneil E, Thibault P, Roux PP. Oncogenic MAPK signaling stimulates mTORC1 activity by promoting RSK-mediated raptor phosphorylation. Curr Biol. 2008 Sep 9;18(17):1269-77. doi: 10.1016/j.cub.2008.07.078. Epub 2008, Aug 21. PMID:18722121 doi:10.1016/j.cub.2008.07.078