PPIB and Alzheimer disease: The channel theory of Alzheimer's disease (AD) was proposed in 1993 by Arispe et al. (1993a,b), who stated that β-amyloid (Aβ) peptide perforates the plasma membrane, leading to the entry of Ca2+ ions and downstream signaling, which eventually causes cytotoxicity (Pacheco et al., 2015; Di Scala et al., 2016).