Control of the G1 phase cyclin-dependent kinases by mitogenic growth factors and the extracellular matrix.

The identification of the nuclear enzymes called cyclin-dependent kinases has profoundly influenced our understanding of cell proliferation. It now seems clear that these enzymes are responsible for mediating progression through each phase of the cell cycle and that the stimulatory effects of both mitogenic growth factors and extracellular matrix on cell proliferation can be fully explained in terms of their effects on the G1 phase cyclin-dependent kinase system. In turn, these effects have provided the long-awaited molecular definitions to the phenotypes of mitogen-dependent and anchorage-dependent growth.