Deletion of one Mmp9 allele in Tg‐SOD1G93A increased the lifespan by 14% and deletion of both Mmp9 alleles (Tg‐SOD1G93AMmp9–/–) by 25%, which is one of the longest prolongations of lifespan ever reported for an intervention in any of ALS mouse models. The gene discussed is MMP9; the disease is amyotrophic lateral sclerosis.