p19INK4d

p19INK4d, also known as CDKN2D, is a protein that plays a crucial role in cell cycle regulation. It is a member of the INK4 family of cyclin-dependent kinase inhibitors. These inhibitors function by binding to cyclin-dependent kinases (CDKs) and preventing them from phosphorylating their target substrates, thereby arresting the cell cycle. Specifically, p19INK4d inhibits CDK4 and CDK6, which are involved in the transition from the G1 phase to the S phase of the cell cycle.

The expression of p19INK4d is tightly regulated and can be induced by various cellular stresses, including DNA damage and oncogene activation. This induction of p19INK4d serves as a protective mechanism, halting cell proliferation to allow for DNA repair or initiating apoptosis if the damage is irreparable. Its role as a tumor suppressor is evident, as its loss or downregulation is frequently observed in various cancers, leading to uncontrolled cell division.

Research has indicated that p19INK4d can also be involved in other cellular processes beyond cell cycle control, such as differentiation and apoptosis. Its precise mechanisms of action and its involvement in diverse cellular pathways are areas of ongoing investigation. The complex regulatory network involving p19INK4d highlights its significance in maintaining cellular homeostasis and preventing oncogenic transformation.