R59949 is a pan diacylglycerol kinase (DGK) inhibitor with an IC50 of 300 nM. R59949 strongly inhibits the activity of type I DGK α and γ and moderately attenuates the activity of type II DGK θ and κ. R59949 activates protein kinase C (PKC) by enhancing the levels of the endogenous ligand diacyl glycerol[1][2][3].