The immunosuppressant leflunomide inhibits lymphocyte proliferation by inhibiting pyrimidine biosynthesis. Cherwinski HM, Cohn RG, Cheung P, Webster DJ, Xu YZ, Caulfield JP, Young JM, Nakano G, Ransom JT J Pharmacol Exp Ther. 1995 Nov; 275(2):1043-9. PMID: 7473131. Abstract CommentRecommendBookmarkWatch