CA9 and hepatocellular carcinoma: Similarly, of the 28 OS-related genes, CA9 regulates the epithelial-mesenchymal transition and is a novel prognostic marker in HCC (38), E2F1 expression has an impact on tumor aggressiveness and affects the prognosis of HCC (14, 15), CYP3A4 (39), HDAC2 (40), and KPNA2 (41) have also been identified as prognostic markers of HCC and are reflected in our findings.