Correlation between c-myc gene expression and phosphatidylinositol (PI) metabolism was studied using seven human kidney cancer cell lines. We found that the exceptional incorporation of 32P into CDP-diacylglycerol (CDP-DG) was observed in only two cell lines, in which c-myc expression was increased among seven cell lines tested. In these two cell lines, PI was also labeled. The other five cell lines indicated the accumulation of radioactive PI, whereas CDP-DG was unlabeled.