<prompt> Which of the following drugs is used as an immunosuppressant but lacks anticancer activity?Methotrexate6-MercaptopurineAzathioprine5-Fluorouracil  <response>: Azathioprine is an antimetabolite that is used as an immunosuppressant but not as an anti-neoplastic drug. It is a prodrug and is conveed to its active metabolite 6-mercaptopurine in the lymphoid cells only. 