CCND1 and hepatocellular carcinoma: In lung cancer and endometrial cancer, PPIA is significantly overexpressed and it causes poor prognosis in patients.[2,14] Recent research has shown that HDAC1, a member of the class I histone deacetylases, plays an essential role in cellular senescence, liver aging, myelination, and adult neurogenesis,[15] and its inactivation may induce liver cancer cell death.[16] Cao et al[1] found that OCT4 upregulates BIRC5 and CCND1 expression to promote HCC cell proliferation.