Therefore, the objective of this study was to evaluate the effect of in vitro CaSR inhibition via a calcilytic agent (NPS-2143) on breast cancer cell proliferation and consequent apoptosis via assessing the caspase 3/7 activation and the expression of the B-cell lymphoma 2 (Bcl-2) antiapoptotic protein. This evidence concerns the gene BCL2 and breast carcinoma.