STAT3 and hepatocellular carcinoma: Using the H4IIE rat hepatoma cell line, Lejeune et al. [18] investigated that IL-22 signaling utilized c-Jun N-terminal kinase (Jak1) and tyrosine kinase (Tyk2) to propagate downstream phosphorylation signals, including mitogen-activated protein kinase (MAPK) signaling pathways [p38 kinase, c-Jun N-terminal kinase (JNK), and extra cellular-signal-regulated kinase 1/2 (ERK1/2), STAT1, STAT3, and STAT5].