SQSTM1 and Alzheimer disease: Our observations that the ability of p62 and optineurin to inhibit sEV secretion depends on their ability to engage ubiquitinated cargo are intriguing in light of the significantly reduced p62 Ser403 phosphorylation in AD brains (Tanji et al., 2014), a phospho-residue required for p62 to bind ubiquitinated cargo (Pilli et al., 2012; Katsuragi et al., 2015; Lim et al., 2015; Matsumoto et al., 2015; Sanchez-Martin and Komatsu, 2018).