The ubiquitin‐proteasomal system, important for maintaining protein quality control, is also compromised in experimental models of familial ALS (Cheroni et al, 2009; Dantuma & Bott, 2014; Scotter et al, 2014), and increased levels of autophagy/mitophagy markers, LC3BII and p62, have been reported in ALS models (Soo et al, 2015; Goode et al, 2016; Oakes et al, 2017). Isolated mitochondria from NSC‐34 SOD1 G93A cells also had higher levels of LC3BII (P = 0.0005) and p62 (P = 0.0073) and that P110 treatment significantly reduced stalled mitophagy (Fig 2D; P = 0.0146 & P = 0.0216, respectively). Furthermore, increased c‐Jun N‐terminal kinase (JNK) phosphorylation, which indicates increased cellular stress, and increased LC3BII conversion and p62‐enhanced accumulation in total lysates, which demonstrate altered autophagic flux, were all significantly normalized by P110 treatment in SOD1 G93A cells (Fig EV3B).