We examined the PLD activities of human renal cancers and found that the PLD2 activity was greatly elevated in almost all cases examined as compared with the adjacent normal region. Western blot analysis showed the increased levels of PLD2 protein, but the PLD1 was not discernible. The oleate-dependent PU) activity was very low but appeared to increase in most cases. Interestingly, the immunohistochemical observations indicated the high expression of PLD2 in the nuclei of clear carcinoma cells. This is the first demonstration which suggests the possible involvement of PLD2 in tumorigenesis of renal cancer.