SOX9 and cholangiocarcinoma: CCA had significantly reduced expression of the hepatocyte marker HNF4A (p = 1.7e−10) (Fig. 2b) and ALB (p = 1.0e−10) (Supplementary Fig. 4B) and increased expression of cholangiocyte marker SOX9 (p = 3.6e−21) as compared to HCC tumors (Fig. 2c).