Although two types of USF, USF1 and USF2, have been reported, it is USF2 that shows the highest binding activity on SF-1 promoter and its knockdown results in down-regulation of SF-1 and also of its target gene CYP19A1 in ectopic endometrium from endometriosis women [17]. The gene discussed is CYP19A1; the disease is endometriosis.