MAPK8 and hepatocellular carcinoma: Treatment with exogenous transforming growth factor beta (TGF-β)1, TGF-β type I receptor (TβRI) inhibitor, TGF-β1 siRNAs, or activator protein 1 (AP-1) inhibitor to MUC1-overexpressing HCC cells revealed that MUC1-induced autocrine TGF-β via JNK/AP-1 pathway promotes the cell migration and invasion.