FGFR2 and cholangiocarcinoma: After annotation and validation, they finally announced that the key factors in CCA include kinases (FGFR1, FGFR2, FGFR3, PIK3CA, ALK, EGFR, ERBB2, BRAF and AKT3), oncogenes (IDH1, IDH2, CCND1, CCND3 and MDM2) and tumor suppressor genes (BRCA1 and BRCA2) [27].