Effects of CU-3 and its derivatives (CU-3-1, CU-3-2, and CU-3-3) on DGKα activity. The 12,000 g supernatant (5 μg) of the extracts from COS-7 cells expressing DGKα was incubated for 5 min in the presence or absence (DMSO alone) of CU-3 (A) and its derivatives: CU-3-1 (B), CU-3-2 (C), or CU-3-3 (D). The values in the absence of CU-3, CU-3-1, CU-3-2, and CU-3-3 (supplementary Fig. 2) were set to 100%.