In conclusion, our observations indicate that the growth of MCF-7 human breast cancer cells induced by E2 is sensitive to pharmacological inhibitors of IP3Rs. Moreover, E2 treatment induced an upregulation of IP3R3 in an estrogen receptor-dependent manner while IP3R3 gene silencing affected both intracellular Ca2+ signalling and cellular proliferation. This evidence concerns the gene ESR1 and breast carcinoma.