PCNA and hepatocellular carcinoma: For HCCN vs. HCV+HCC (tumor stage), top associated network functions for differentially expressed genes (Table 4B) were: 1) GADD 45 signaling, 2) Cell cycle control of chromosomal replication, 3) Estrogen-mediated S-phase entry, 4) Cell cycle: G2/M DNA damage checkpoint regulation, 5) Cyclins and cell cycle regulation.