PCNA and hepatocellular carcinoma: Immunohistochemical analysis of tumors revealed significant increases in the HCC marker α-fetoprotein (AFP), proliferation marker proliferating cell nuclear antigen (PCNA), LSF target gene osteopontin (OPN) and thymidylate synthase (TS) and angiogenesis marker CD31 only in control animals but not in FQI1- or FQI2-treated animals (Figure 1E).