Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Overexpression of cyclin D may disrupt the Rb pathway at several points: (a) it competes with p16 for interaction with cdk4/6, which then becomes activated to phosphorylate Rb (top); (b) cyclin D-cdk4/6 complexes sequester the cdk inhibitors p21 and p27 so that they are unavailable to block cdk2 (bottom). Cyclin E-cdk2 can then act downstream of Rb to initiate cell cycle progression into S phase. See text for details.
