AS.020.305 Midterm: cell bio final study sheet (dragged) 7
Document Summary
Other cell types withdraw from the cell cycle only transiently and retain the ability to reassemble the cell-cycle control system quickly and reenter the cycle. Most liver cells, for example, are in g0, but they can be stimulated to divide if the liver is damaged. Still other types of cells, including fibroblasts and some lymphocytes, withdraw from and re-enter the cell cycle repeatedly throughout their lifetime. Mitogens*stimulate*g1acdk*and*g1/sacdk*activities: mitogens interact with cell-surface receptors to trigger multiple intracellular signaling pathways. One major pathway acts through the small gtpase ras, which leads to the activation of a map kinase cascade. This leads to an increase in the production of gene regulatory proteins, including. Myc is thought to promote cell-cycle entry by several mecha-nisms, one of which is to increase the expression of genes encoding g1cyclins (d cyclins), thereby increasing gr-cdk (cyclin d-cdk4) activity. In the absence of mitogenic stimulation, e2f-dependent gene expression is inhibited by an inter- action between.