ACP5 and postmenopausal osteoporosis: In a rat model of postmenopausal osteoporosis, combination therapy of alfacalcidol with ZA demonstrated significant preserved trabecular microstructure and cortical bone density with decreased serum TRAcP level than alfacalcidol or ZA alone.32 Yu et al.33 illustrated that the combination of ZA with everolimus was able to relieve the cancer-induced bone devastation greatly than individual treatment, as further assessed by the significant decreased layer of crosslinked NTX, the biomarker of osteolytic cell activity in combination group.