CYP1B1 and neoplasm: Interestingly, RSV has been reported to downregulate Cyp1b1, thereby increasing apoptosis induced by antimetabolites such as 5-FU and gemcitabine in gemcitabine-chemoresistant cholangiocarcinoma (Mz-ChA-1, HuCC-T1, CCLP1, and SG231) tumor models.