In accordance with the results obtained in computational studies, we ascertained the molecular mechanisms involved in the biological responses to a calix[4]pyrrole derivative [meso-octamethylcalix[4]pyrrole (C4PY)] (Fig. 1), which had the ability to act as a GPER antagonist in breast cancer cells and CAFs used as model systems. This evidence concerns the gene GPER1 and breast carcinoma.