It has been reported that proteolytic cleavage of agrin, a proteoglycan involved in NMJ development, maturation, and AChRs clustering [102], induces early onset sarcopenia in young adult mice [103], whereas the injection of a neurotrypsin-resistant agrin fragment stabilized NMJ and improved the phenotype of neurotrypsin-overexpressing mice [104]. Here, AGRN is linked to sarcopenia.