IMPDH2 is a cytosolic enzyme which belongs to the IMPDH/GMPR family. IMPDH2 catalyzes the NAD-dependent oxidation of inosine-5'-monophosphate into xanthine-5'-monophosphate, which is then converted into guanosine-5'- monophosphate. 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).