Protein kinase D (PKD) is a serine/threonine protein kinase that is activated by diacylglycerol, commonly downstream of PKC signaling. The three human PKD isoforms target a variety of proteins to alter cell proliferation, survival, invasion, and protein transport. CRT5 is a pyrazine benzamide that prevents activation of all three isoforms of PKD in endothelial cells treated with VEGF (IC50s = 1, 2, and 1.5 nM for PKD1, PKD2, and PKD3, respectively). It has little effect on a panel of additional kinases when given at 1 μM. CRT5 blocks phosphorylation of PKD1 on Ser916 and PKD2 on Ser876, but does not affect PKC-dependent PKD phosphorylation or PKD autophosphorylation. It also decreases VEGF-induced endothelial migration, proliferation, and tubulogenesis.
