GNRH1 and breast cancer: However, previous radioligand-binding and dose–response studies on MCF-7 human breast cancer cells [27], αT3-1 human gonadotrope cells [36], and human GnRHR-transfected COS-7 cells [37,38] have suggested that the applied concentration range of [d-Lys6(FITC)]–GnRH-I (10−7–10−5 M) on EBC-1 cells was several orders of magnitude higher than the ypothetical GnRHR saturation concentration (<10−8 M).