Lipidomic analysis of U2OS, CEPT1-KO, and CHPT1-KO cells.A and B, total PC, PE, and lyso-lipids were quantified as described in the Experimental procedures. C and D, the major molecular species of diacyl-PC and diacyl-PE were quantified and expressed as a percent of total. Results are the mean and SD of 3 to 6 biological replicates; significance was determined by unpaired t tests with U2OS cell controls. CEPT1, choline/ethanolamine phosphotransferase 1; CHPT1, choline phosphotransferase 1; PC, phosphatidylcholine; PE, phosphatidylethanolamine.