Background：Hydroxysteroid （17-beta） dehydrogenase 1 catalyzes the final step in the formation of estradiol and testosterone from estrone and androstenedione, respectively. Ovarian granulosa cells and breast tissue both express HSD17B1. Other tissues that express HSD17B1 include testis, placenta, uterus, prostate and adipose tissue. HSD17B1 functions as a homodimer and prefers NADP（H） over NAD（H） for oxidation and reduction. The gene encoding human HSD17B1 maps to chromosome 17q12-q21. The importance of HSD17B1 to estradiol production suggests the specific inhibition of HSD17B1 may aid in breast cancer therapy.
