TBCE and Hepatic fibrosis: PDGF, a potent proliferative cytokine secreted by KCs, can induce tyrosine phosphorylation and activate the downstream signaling molecule SHP-2 (Src homology region 2 domain-containing protein tyrosine phosphatase-2) by binding to the cell-surface receptors on HSCs, and then exacerbate liver fibrosis in mice (69–71).