CCNB1 and neoplasm: Overexpression of the mouse mPer2 gene has been shown to inhibit both tumor formation, and cell proliferation by decreasing Cyclin B1 and Cyclin A2 expression, while promoting p53 transcription to accelerate apoptosis (Hua et al., 2006; Lee, 2006; Hua et al., 2007; Wood et al., 2008; Yang and Stockwell, 2008).