PCNA and hepatocellular carcinoma: A single intraperitoneal injection of DEN (15 mg/kg) in 15‐day‐old male mice induces hepatocellular carcinogenesis, providing an animal model for HCC research in vivo.7, 42 In DEN‐induced HCC mouse tissues, the results showed that PTTG1 was upregulated, accompanied by increased c‐myc and PCNA expression.