ESR1 and postmenopausal osteoporosis: Riggs and colleagues(46) hypothesized that the greater bone loss in postmenopausal osteoporosis is the result of impaired responsiveness of bone to postmenopausal levels of sex steroids and ascribed the impaired bone responsiveness to the polymorphisms of the genes for the estrogen receptors or the postreceptor estrogen signaling pathway.(46) In this study we clearly demonstrated that the bone cells from osteoporotic postmenopausal women expressed much lower levels of ER-α36 than bone cells from normal postmenopausal women.