Increased levels of p53 in ALS patients suggest a possible down-regulation of proteins that negatively regulate p53 (e.g., murine doble minute 2 (mdm2)) or a reduced degradation of p53 by the proteasome (a mechanism damaged in neurodegenerative diseases and, in part, responsible for the accumulation of abnormal protein aggregates) [36]. The gene discussed is TP53; the disease is amyotrophic lateral sclerosis.