Human Inosine Monophosphate Dehydrogenase type 2 (IMPDH(II)) catalyzes the committed step of de novo biosynthesis of guanine nucleotides. It is a homotetratmer with each subunit approximately 58 kD. Type (II) IMPDH appears to be inducible. Its expression is elevated during proliferation and decreases during differentiation. Inhibition of IMPDH(II) reduces intracellular guanine nucleotide pools and inhibits cellular proliferation. The inhibition of IMPDH(II) makes it a viable candidate for therapeutic targets in immunosuppression, psoriasis, anticancer and antiviral chemotherapy.