CDKN2A and neoplasm: Of note, the INK4 protein p16 can be induced by growth factor-β (TGFβ) signaling, and is able to bind to CDK4 and 6, decreasing cell progression from G1 phase to S phase, and therefore acting as a tumor suppressor, in opposition to the ER and CDK4/6 signaling stimuli [6,7].