AGRN and sarcopenia: The agrin cleavage process influences agrin function in normal physiology as well as pathology, as NMJ maturation is dependent upon normal agrin cleavage and aberrant agrin cleavage is linked to neurological disease such as mental retardation and neuromuscular pathologies such as muscular dystrophy and sarcopenia (Bentzinger et al., 2005; Reif et al., 2007; Frischknecht et al., 2008; Bütikofer et al., 2011; Drey et al., 2013; Marzetti et al., 2014; Pribiag et al., 2014; Kalinkovich and Livshits, 2015; Landi et al., 2016).