ESR1 and breast cancer: Some reports shows positive correlation between KISS1 mRNA expression or KISS1R signaling and breast cancer progression and metastasis[15, 16], while the results of other reports indicate that KISS1 is required for metastasis suppression and maintenance of tumor dormancy[30, 41–43].To elucidate such discrepancy, Cvetkovic ́et al. examined potential activity of KP-10 on estrogen receptor positive and negative cell lines and demonstrated that KP-10 stimulates invasion of estrogen receptor negative MDA-MB-231 breast cancer cells via transactivation of the epidermal growth factor receptor (EGFR).