This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
All are true about immunosuppressants except? 
Select and explain. 
A. Tacrolimus inhibits calcineurin pathway, B. Steroids binds to cytosolic receptors and heat shock proteins, C. Mycophenolate inhibits purine synthesis GMP dehydrogenase, D. Sirolimus will block kinase in the IL-2 receptor pathway
C: Mycophenolate inhibits purine synthesis GMP dehydrogenase
Answer: C: Mycophenolate inhibits purine synthesis GMP dehydrogenase 
Explanation: Ans. is 'c' i.e., Mycophenolate inhibits purine synthesis GMP dehydrogenase o Mycophenolate inhibits purine synthesis inosine monophosphate (IMP) dehydrogenase (not GMP dehydrogenase). About other options o Tacrolimus enters target cells and binds to FKBP. The complex then inhibits calcineurin response of the helper T cell to antigenic stimulation fails. o Glucocoicoids bind cytosolic receptors and heat shock proteins, block transcription of IL-1, 2, 3, 6, IFN-y and TNF-cs o Sirolimus complexes with FkBP -12 and then blocks p7deg S6 kinase in the IL-2 receptors pathway for proliferation.