Deficient 17β-hydroxysteroid dehydrogenase type 2 expression in endometriosis: failure to metabolize 17β-estradiol. - Zeitoun,K.; Takayama,K.; Sasano,H.; Suzuki,T.; Moghrabi,N.; Andersson,S.; Johns,A.; Meng,L.; Putman,M.; Carr,B.; Bulun,S.E. (J Clin Endocrinol Metab, 1998)