FIGURE 2.

The inhibitory activities of CID755673 and CID797718. A, inhibition of recombinant human PKD1 in vitro. The kinase activity of PKD1 was assayed in the presence of 10 different concentrations of CID755673 by a radiometric PKD kinase assay. The IC₅₀ values were the mean ± S.E. of at least three independent experiments with triplicate determinations at each drug concentration in each experiment. The data were plotted as a function of drug concentration and a representative graph is shown. B, inhibition of endogenous PKD1 activity by CID755673 in cells. LNCaP cells were pretreated with different doses of CID755673 or CID797718 for 45 min, followed by PMA stimulation at 100 nm for 20 min. Cell lysates were subjected to immunoblotting for p-S742-PKD1 and p-S916-PKD1. PKD1 was blotted as loading control. Note that the low p-S916-PKD1 signal in lane 2 (PMA alone) was likely caused by uneven loading. The experiment was repeated five times and a representative blot is shown.