MAPT and Alzheimer disease: Furthermore, other studies demonstrated that transference of damaged neuronal cell-derived exosomes with APP, γ/β secretases, Aβ peptides, APP-CTF, ubiquitins, modified ubiquitin ligases and tau protein to adjacent neurons can lead to AD propagation (Chen et al., 2017; Yuyama and Igarashi, 2017; Zheng et al., 2017; Miranda et al., 2018).