Synergistic regulation of Lcn2 and Tac1 promoter activities by leptin and forskolin in PC-12 pheochromocytoma cells. PC-12 cells stably expressing LEPRb were transiently transfected with the Tac1 or Lcn2 reporter gene constructs. Cells were left untreated or treated with leptin (100 ng/ml) and/or forskolin (10 μg/ml) for 24 hours before lysis. Luciferase activities were determined from duplicate wells and data were normalised to β-galactosidase activities. Data are expressed as fold stimulation by the treatment relative to unstimulated cells. Results are means +/- SD of three (Tac1 promoter) or four (Lcn2-promoter) independent experiments.