Time dependent action of GnRH (leuprolide acetate) on Smad3, Smad4 and Smad7 (arrows) mRNA expression in human endometrial surface epithelial cells (HES) and isolated endometrial stromal cells (ESC). Serum-starved cells were treated with GnRH (0.1 μM) for 2 to 12 hrs and total RNA was isolated from treated and untreated control (Ctrl) cells and subjected to semi-quantitative RT-PCR co-amplifying Smads and G3PDH (lower bands) mRNA shown from a representative experiment. The bar graph show the mean ± SEM of fold change of ratio of Smad7:G3PDH mRNA expression from three independent experiments. b, c, d, and e and c' and are significantly different from a and a', respectively (p < 0.05). M = DNA marker.