References
PMID:23140366
PMID:17055429
p16 and p15 activates the pRB tumor supressor by inhibiting the cyclin dependent kinase CDK4 and CDK6, which promotes proliferation. The inhibition of CDK4 and CDK6 ability to phosphorylate Rb, maintains Rb-family protein in a hypophosphorylated state which promotes G1 cell cycle arrest