PPP1R15A and hepatocellular carcinoma: The function studies also showed that the PPP1 inhibitor OA recovered the cell viability suppressed by the combination of sorafenib and 3-HAA (Fig. 4F) and PPP1R15A knockdown restored the HCC xenograft growth inhibited by the combination of sorafenib and 3-HAA, evidenced by the tumor growth curve and the final tumor weight (Fig. 4G).