Figure 3.

Breast cancer cells continuously exposed to tamoxifen exhibit higher [Ca²⁺]_i mobilization than untreated controls when are stimulated with 17β-estradiol or G1. Continuously treated and untreated MCF-7 cells were cultured, detached and loaded with Indo-AM calcium probe before stimulation with 10 nM 17β-estradiol (E2) (A) or 100 nM G1 (B), a specific synthetic agonist of GPER-1. The area under the curve was calculated and graphed to assess the magnitude of the response in each condition. BL, baseline. (C) Preincubation for 5 min with 1,000 nM G15 significantly decreased [Ca²⁺]_i mobilization in tamoxifen-treated cells; additional controls using triton X-100 and EGTA are also depicted. Results are shown as mean ± SEM (n = 3) *P < 0.05; between tamoxifen-treated cells and untreated controls.