MAPK3 and hepatocellular carcinoma: Consistent with this, IF assays confirmed co-localization of APPLE-Flag with p-ERK1/2, PPP1CB, PPP1R12A, and PPP2R2A in HCC cells (Fig. 7G), supporting the notion that APPLE sustains ERK1/2 phosphorylation by binding to and inhibiting PP1/PP2A phosphatase activity.