IMPDH2 Full-Length MS Protein Standard (NP_000875), Labeled with [U- 13C6, 15N4]-L-Arginine and [U- 13C6, 15N2]-L-Lysine, was produced in human 293 cells (HEK293) with fully chemically defined cell culture medium to obtain incorporation efficiency at Creative-Proteomics. This gene encodes the rate-limiting enzyme in the de novo guanine nucleotide biosynthesis. It is thus involved in maintaining cellular guanine deoxy- and ribonucleotide pools needed for DNA and RNA synthesis. The encoded protein catalyzes the NAD-dependent oxidation of inosine-5-monophosphate into xanthine-5-monophosphate, which is then converted into guanosine-5-monophosphate. This gene is up-regulated in some neoplasms, suggesting it may play a role in malignant transformation.