Janus-associated kinases (JAKs) are cytoplasmic tyrosine kinases that are required for activating the signaling of certain cytokines and growth factor receptors. Many myeloproliferative diseases have been linked to a mutation in JAK2 in which a switch from valine to phenylalanine occurs at the 617 position (V617F). JAK2 Inhibitor V is an inhibitor of the autophosphorylation of wild type and V617F mutant forms of JAK2, displaying IC50 values between 10 and 30 μM. It has no effect on Tyk2 or c-Src kinase function. JAK2 Inhibitor V blocks the proliferation of erythroleukemia cells and human hematopoietic progenitor cells expressing JAK2-V617F.
