CD274 and cholangiocarcinoma: However, CSC-like characteristics including high aldehyde dehydrogenase activity, reduced production of reactive oxygen species and a dormant state in the cell cycle were favored following knockdown of PD-L1 in cholangiocarcinoma cell tumors inoculated into mice compared to high PD-L1 expressing tumors (184), indicating that intrinsically PD-L1 may have different roles in different cancer types.