Initial assessment of an immortalized human breast epithelial cell line (SVCT) and four human breast cancer cell lines (MCF-7, ZR-75-1, T47D and MDA-MB-231) indicated that these models did not possess detectable levels of endogenous GnRH receptor at the cell surface when analysed using a binding assay employing a 125I-labelled GnRH analog (His5-D-Tyr6-GnRH-I). Here, GNRH1 is linked to breast cancer.