SERPINE2 and Alzheimer disease: SERPINE2 (Serpin Family E Member 2), also termed as Protease Nexin-1 (PN-1), is a member of the serpin family of proteins, which can inhibit serine proteases including thrombin, urokinase, plasmin, and trypsin (Madjene et al., 2021), whose role in AD has not been fully understood.