TAM (10 nM) acts as an agonist in MCF7/IGF-1R stimulated by IGF-1. (a) Dose dependence of TAM resistance on IGF-1. (b) Antagonistic effect of 10 nM TAM on 1 nM E2-induced cell proliferation. (c) Antagonistic effect of 10 nM TAM on 1 nM E2-induced ERE-Luc activity. (d) Agonistic effect of 10 nM TAM on 100 ng/mL IGF-1-stimulated MCF7/IGF-1R cells. (e) ERE-Luc activity induced by agonistic TAM (10 nM) in IGF-1-stimulated MCF7/IGF-1R cells. (f) ER dependence of agonistic effect of TAM (10 nM) in MCF7/IGF-1R cells. siCtrl, siRNA control; siERα, siRNA ERα. Results are representative of three individual experiments. Luciferase activity was normalized to DMSO control. Error bars represent ± SD. *P < 0.05.