The tumor suppressor protein p16INK4a.

The tumor suppressor protein p16INK4a (inhibitor of CDK4) is one of the most direct links between cell-cycle control and cancer. The p16INK4a gene is frequently inactivated in human tumors, and inheritance of mutant alleles results in susceptibility to several types of cancer. p16INK4a is part of a cell-cycle regulatory pathway that converges in the tumor suppressor protein Rb. The mechanisms that regulate p16INK4a are starting to be characterized.