IMPDH2 is a member of the IMPDH/GMPR family. IMPDH2 catalyzes the NAD-dependent oxidation of inosine-5’-monophosphate into xanthine-5’-monophosphate， which is afterward converted into guanosine-5’-monophosphate. IMPDH2 is the rate-limiting enzyme in the de novo guanine nucleotide biosynthesis. IMPDH2 is consequently involved in maintaining cellular guanine deoxy- and ribonucleotide pools required for DNA and RNA synthesis. In addition， IMPDH1 and IMPDH2 are targets for the important immunosuppressive drug， mycophenolic acid（MPA). Furthermore， the IMPDH2 gene is up-regulated in some neoplasms， suggesting it may have a role in malignant transformation.
