FIG. 1.
Estrogen stimulates proliferation of thyroid cells. Effect of E2 on proliferation of Nthy-ori 3-1 and BCPAP was determined by the trypan blue dye exclusion assay. Cells were seeded at a density of 1 × 105 cells per well and allowed to adhere overnight. The starvation medium (10% charcoal-dextran-treated FBS) was then added for 24 hours, followed by stimulation with 10−8 M E2 for 24 hours. MCF-7, estrogen-responsive human breast cancer cells were used as a positive control. Cell growth is expressed as percent increase in viable cells + E2 (black bars) relative to untreated control (white bars). The asterisk denotes statistically significant increase (p < 0.05) in the experimental groups compared with controls. E2, estradiol; FBS, fetal bovine serum.