Neuropeptide Y receptor 1 gene expression was augmented when estrogen receptor-positive BC cells/experimental animal models were treated with estrogens, whereas the expression of neuropeptide Y receptor 1 decreased in estrogen receptor-positive BC cells resistant to endocrine treatments (fulvestrant, tamoxifen, estrogen deprivation) in vivo and in vitro [197]. The gene discussed is ESR1; the disease is breast cancer.