How Do Extracellular Signals Affect The Cell Cycle?

How Do Extracellular Signals Affect The Cell Cycle? Some extracellular signal proteins, including PDGF, can act as both growth factors and mitogens, stimulating both cell growth and cell-cycle progression. This functional overlap is achieved in part by overlaps in the intracellular signaling pathways that control these two processes. How do you extracellular signals affect a