In the estrogen receptor (ER) + human breast cancer cell line, MCF7, ghrelin at concentrations of 0–1,000 nM had no effect on cell proliferation (62), whereas Cassoni et al. demonstrated that ghrelin, des-acyl ghrelin, as well as a number of ghrelin mimetics, significantly inhibited cell proliferation (47). This evidence concerns the gene ESR1 and breast cancer.