SMAD3 and cancer: 1) CHI3L1 promoted cancer cell proliferation by regulating cell cycles; 2) CHI3L1 promoted cancer cell invasion and metastasis by acting on the EMT pathways; 3) CHI3L1 regulate liver fibrosis potentially by regulating the TGF-β signaling pathways; 4) CHI3L1 may has direct kinase activities or activate a kinase to phosphorylate SMAD2 and SMAD3.