“…However, the same strategy of progesterone supplementation, when used in endometrial explants, does not affect apoptosis, despite effectively maintaining the histological integrity of explanted tissue (Li et al, 2005). In isolated endometrial cells in culture, progesterone actually induces apoptosis (Li et al, 2001;Choksuchat et al, 2009;Tang et al, 2009), an effect that may be consistent with reports of antiapoptotic actions of mifepristone in endometrial biopsies from progestogen users (Jain et al, 2006). Furthermore, progesterone physiologically down-regulates endometrial Bcl-2 expression, which decreases at the early secretory phase (von Rango et al, 1998) and increases upon mifepristone administration (Critchley et al, 1999;Fig.…”