PCNA and colorectal carcinoma: To provide further evidence regarding the mechanisms underlying the effects of VCP on CRC cells, the present study examined the expression levels of proteins associated with CRC cell proliferation (p21, cyclin D1, CDK4, cyclin E, CDK2, Ki-67, and PCNA) and apoptosis (Bcl-2/Bax, Bcl-xL, cleaved-PARP, cleaved-caspase-3, p-STAT3, and STAT3) by western blot analysis.