In a study on liver cancer in transgenic mice with CCNA2 conditional knockout, liver tumors in WT mice could be detected as early as 2 months, and all mice developed liver tumors within 4 months; for CCNA2liv−/− (CCNA2 knockout) mice, one of six mice developed liver tumors by 4 months, whereas the majority of them displayed liver tumors after 6 months (55). The gene discussed is CCNA2; the disease is liver cancer.