Moreover, there was a positive correlation between USP14 and p-MEK1/2 (Spearman r1⁄4 0.562; P < 0.05), or USP14 and p-ERK1/2 (Spearman r 1⁄4 0.735; n 1⁄4 40; P < 0.05) after staining for USP14, p-MEK1, and p-ERK1/2 in the tissue of 15 HCC cases (Fig. S2e and f). Here, MAPK3 is linked to hepatocellular carcinoma.