Several studies have shown that TGF-β1 is increased in the peritoneal fluid, peritoneum and ectopic endometrium of women with endometriosis12, 13, 14, 15, suggesting that the same over production of TGF-β1 that is seen in tumours and the surrounding stroma is also true for endometriosis lesions and the surrounding peritoneum. The gene discussed is TGFB1; the disease is endometriosis.