PPP3CA and cholangiocarcinoma: Most of these proteins were involved in blood coagulation (16.44%), the integrin signaling pathway (12.33%), inflammation mediated by the chemokine and cytokine signaling pathway (9.59%), cytoskeletal regulation by Rho GTPase (8.22%), and the CCKR signaling map (5.48%), etc. Based on the results of the bioinformatic analysis and the literature review, we selected PRDX2, BGN, LUM, and PPP3CA as novel candidate biomarkers of CCA, as the expression profiles of these proteins in CCA were rarely reported.