regulates cell cycle progression from G1 to S phase
Cyclin D1, also known as CCND1, is a protein that plays a crucial role in regulating the cell cycle, specifically the transition from the G1 phase to the S phase, where DNA replication occurs. It acts as a regulatory subunit for certain enzymes called cyclin-dependent kinases (CDKs), and its overexpression is often associated with various types of cancer, as it can lead to uncontrolled cell proliferation.