GPLD1 and autosomal dominant polycystic kidney disease: Figure 3A shows that both PLD1 and PLD2 inhibitors reduced specifically the phosphorylation of PLD1 and PLD2, respectively. Using an enzymatic assay to correlate the inhibition of phosphorylation with PLD activity we found that both PLD inhibitors reduced total PLD activity in ADPKD and OX161 cell lysates (Figure 3B).