MAPK8 and neoplasm: Taken together, HBV or HCV components and pro-inflammatory cytokine additively activate JNK to shift Smad phospho-isoform signaling from the tumor-suppressive TβRI/pSmad3C pathway to the carcinogenic JNK/pSmad3L pathway together with the fibrogenic pSmad2L/C pathway, accelerating liver fibrosis and promoting hepatocarcinogenesis.