Relative luciferase activities of per-luc, tim-luc, vri-luc, Pdp1-luc, and cwo-luc in the presence of 0 (–) or 100 (+) ng pAc5.1-dCtBP alone, or 0 (–), 100 (+), 400 (++) ng pAc5.1-dCtBP (dCtBP), or 400 (++) ng pAc5.1-dCtBP-G183A/G186A (dCtBP -DM) in conjunction with 100 ng pAct-Clk are represented. The luciferase activity was normalized by the activity of Renilla luciferase as a control reporter, and then the activity was normalized by the activity of pAct-Clk alone. RLU means relative luminescence unit. dCtBP regulates the promoter activity of core clock genes. The difference between values without Clk was calculated by t test. The difference between the values with Clk was calculated by the Tukey’s test, and asterisks indicate significant differences between two values (*P<0.05 and **P<0.01). These experiments were performed independently three times (or four in some cases) and error bars represent S.E.M.