This peptide hormone, produced in the hypothalamus, stimulates the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) by the pituitary gland, which in turn induces steroid production in the gonads, playing a key role in the regulation of the reproductive system but also enhancing the growth and progression of estrogen-dependent tumors, as occurs with breast cancer [80,81]. The gene discussed is PLOD1; the disease is breast cancer.