CCND1 and neoplasm: Interestingly, miR-15a, -15b and -16 are known as tumor-suppressor miRNAs as their activity directly represses the expression of anti-apoptotic genes such as Bcl2 (validated in human, mouse and rat23, 24), Ccnd1 (validated in human, mouse and rat25) and protein carboxyl-O-methyltransferase (Pcmt1; validated in human26).