TCF7L2 and biliary tract cancer: SOX9 is an SRY‐containing homeobox transcription factor[38] active in biliary development,[39, 40] and has been linked to a worse prognosis in biliary tract cancer.[41] Likewise, TCF7L2 acts as a co‐effector of the Wnt/β‐catenin pathway involved in biliary development[42, 43] and carcinogenesis.[44, 45, 46] Among SOX and TCF family members, SOX9 and TCF7L2 were the most expressed in GBC (Figure S2H, Supporting Information).