CAFs can fuel CCA overgrowth via paracrine mechanisms [53], involving secretion of several factors (Table 2), such as HGF, TGF-β, PDGF-BB, heparin-binding epidermal growth factor (HB-EGF), and SDF-1 (Figure 1) [51]. Here, CXCL12 is linked to cholangiocarcinoma.