CCND1 (Cyclin D1): CCND1 is a gene that encodes cyclin D1, a key protein involved in regulating the cell cycle. Cyclins, including cyclin D1, coordinate the progression of the cell cycle, with CCND1 playing a crucial role in promoting cell division and proliferation. Dysregulation of CCND1 is commonly associated with various cancers, highlighting its significance as an important oncogene.