PDGFRB and intrahepatic cholangiocarcinoma: In a study by Sha et al., CAFs were identified on the basis of positive staining for FAP, α-SMA, FSP-1, and PDGFR-β, and intrahepatic cholangiocarcinoma (ICC) cells were observed to proliferate faster in CAF-conditioned media when compared to normal fibroblast conditioned media [57].