In line with proteomic data (Figures 6A, C), total ERK1/2 protein levels were significantly decreased in TPC2 KO HCC cell lines (Figures 7C-F, G, S7A), while melanoma cell lines and TRPML1 KO cells showed no such reduction (Supplementary Figures S7B, C). Here, MAPK3 is linked to hepatocellular carcinoma.