<prompt> Methotrexate an older cancer treatment medication can be used as first-line therapy for rheumatologic and psoriatic diseases. One of the side effects of methotrexate usage mimics which one of the following vitamin deficiencies?Pyridoxine B6Biotin B7Niacin B2Folate B9  <response>: Methotrexate targets and inhibits FH2 reductase, which catalyzes the reduction of FH2 to FH4 . Thus, in the presence of methotrexate, FH4 cannot be regenerated, and the body becomes functionally folate deficient. Methotrexate does not interfere with the absorption or reactions of the other B vitamins listed as potential answers. 