Figure 1From: Transforming growth factor-β and breast cancer: Cell cycle arrest by transforming growth factor-β and its disruption in cancerThe cell cycle. Cell cycle progression is governed by cyclin-dependent kinases (cdks), the activities of which are regulated by binding of cyclins, by phosphorylation and by the cdk inhibitors [the inhibitor of cdk4 (INK4) family: p15, p16, p18 and p19; and the kinase inhibitor protein (KIP) family: p21, p27 and p57].Back to article page