CDK6 (Cyclin-Dependent Kinase 6): CDK6 is a protein that, when paired with D-type cyclins, plays a crucial role in regulating the cell cycle, particularly the transition from the G1 to S phase. It is vital for cell proliferation and differentiation. Dysregulation of CDK6 has been linked to various cancers, making it a significant target for cancer treatments, especially in tumors exhibiting CDK6 overexpression or abnormal activity.