An inhibitor of all three PKD isoforms (IC50s = 3.2, 0.6, and 0.7 μM for PKD1, PKD2, and PKD3, respectively); cell permeable, blocking the phosphorylation of PKD1 on Ser916 (an autocatalytic target) in LNCaP prostate cancer cells in response to phorbol esters (EC50 = 10 μM).