During the genesis of CCA, both PSC and parasitic infections cause cholestasis and chronic inflammation of the bile duct, which can induce the epithelial cells to produce a variety of cytokines including IL-6, IL-8, TGF-β, TNF-α, platelet-derived growth factor (PDGF), and epidermal growth factor (EGF) (Table 2) [23]. This evidence concerns the gene TGFB1 and cholangiocarcinoma.