SOD1 and neuroblastoma: Another E3 ligase called Smurf1 (Smad ubiquitination regulatory factor 1) was shown to promote K63-type ubiquitin attachment to SOD1, which enhanced aggresome formation and eventual autophagic degradation of misfolded SOD1 in a mouse neuroblastoma cell line (Neuro-2a, aka N2a) and a human neuroblastoma cell line SH-SY5Y [90].