Signal cell growth

The last part of this account will be devoted to protein kinases and protein phosphatases and some recent results we have obtained for them. Protein kinases and phosphatases are signaling biomolecules that control the level of phosphorylation and dephosphorylation of tyrosine, serine or threonine residues in other proteins, and by this means regulate a variety of fundamental cellular processes including cell growth and proliferation, cell cycle and cytoskeletal integrity. 

Shaw RJ, Cantley LC (2006) Ras, PI(3)K and mTOR signalling controls tumor cell growth. Nature 441 424-430... 

Wullschleger S, Loewith R, Hall MN (2006) TOR Signaling in growth and metabolism. Cell 124 471-484... 

Barbero S, Bonavia R, Bajetto A, et al. Stromal cell-derived factor la stimulates human glioblastoma cell growth through the activation of both extracellular signal-regulated kinases 1/2 and AKT. Cancer Res 2003 63 1969-1974. 

Raff I am not aware of any example where a limit to cell growth has been demonstrated in vivo. Generally, if you increase the amount of cell growth factor available, cells will get bigger. Thus the levels of extracellular signals can influence cell size in an animal. 

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