PDGFRB and cholangiocarcinoma: In vitro and murine xenograft experiments showed that CAFs express Platelet Derived Growth Factor Receptor β (PDGFR-β), and that cultured cholangiocarcinoma cells secrete the PDGFR-β ligand Platelet Derived Growth Factor-D (PDGF-D) resulting in fibroblast migration and recruitment [156].