The expression of estrogen responsive genes common to breast cancer: AREG, CYP19A1, EGFR, ESR2, FOS, IGF1, KRAS, NCOA1, NCOR1, NR2F6, PGR, STC2 genes was upregulated in human endometriosis lesions [53,54,55]. The gene discussed is FOS; the disease is endometriosis.