Because of our long-standing interest in defining the mechanisms by which MAL2 regulates polarized hepatic protein sorting, we chose to examine MAL2 expression levels in resected human tissues from HCC and for comparison, from CC (another liver-derived cancer) and RCC using an analytically validated immunohistochemistry (IHC) test for clinical and diagnostic applications. This evidence concerns the gene MAL2 and cholangiocarcinoma.