In addition, the expression of the BCAA degradation pathway in extrahepatic cholangiocarcinoma and gallbladder cancer was similar to the expression in ICC, and in hepatocellular carcinoma (HCC), both BCAT1 and BCAT2 were highly expressed in tumour samples as previously reported [25] (Supplementary Fig. S5). Here, BCAT2 is linked to intrahepatic cholangiocarcinoma.