[CAS NO. 167869-21-8]  PD98059

PD98059 inhibits either basal MEK1 or a partially activated MEK produced by mutation of serine at residues 218 and 222 to glutamate (MEK-2E) with IC50 of 2 μM. PD98059 does not inhibit the MAPK homologues JNK and P38. PD98059 is highly selective against MEK, as it does not inhibit a number of other kinase activities including Raf kinase, cAMP-dependent kinase, protein kinase C, v-Src, epidermal growth factor (EGF) receptor kinase, insulin receptor kinase, PDGF receptor kinase, and phosphatidylinositol 3-kinase. PD98059 inhibits PDGF-stimulated activation of MAPK and thymidine incorporation into 3T3 cells with IC50 of ~10 μM and ~7 μM, respectively. PD98059 potently prevents the activation of MEK1 by Raf or MEK kinase with IC50 of 4 μM, and weakly inhibits the activation of MEK2 by Raf with IC50 of 50 μM. PD98059 does not inhibit the activation of MEK homologues MKK4 and RK kinase that participate in stress and interleukin-1-stimulated kinase cascades in KB and PC12 cells, and the activation of p70 S6 kinase by insulin or epidermal growth factor in Swiss 3T3 cells. PD98059 completely blocks the nerve growth factor (NGF)-induced differentiation of PC12 cells without altering cell viability. PD98059 inhibits the proliferation of RAW264.7 cells in the culture containing RANKL in a dose-dependent manner, resulting in an apparent decrease of TRAP-positive cells.