In hepatic tumor cells, DUSP9 negatively regulates the RAS/RAF/MEK/ERK signal by dephosphorylating ERK1/ERK2 and a low level of DUSP9 is correlated with an elevated level of phospho-ERK1/2 in hepatocellular carcinoma (HCC) samples [15]. Here, MAPK1 is linked to hepatocellular carcinoma.