Significantly, cell cycle regulators including p-RB, PCNA, CYCLIN A, CYCLIN D1, and CYCLIN E were profoundly downregulated by combining alpelisib and palbociclib (Fig. 4f; Supplementary Fig. S27), supporting the synergistic effects in inhibiting HCC cell proliferation. This evidence concerns the gene PCNA and hepatocellular carcinoma.