Mechanistic studies revealed that ALT-007 enhances proteinhomeostasis in Caenorhabditis elegans and mouse models of aging and age-related diseases, such as sarcopeniaand inclusion body myositis (IBM); this effect is mediated by a specificreduction in very-long chain 1-deoxy-sphingolipid species, which accumulatein both muscle and brain tissues of aged mice and in muscle cellsfrom IBM patients. Here, GPT is linked to inclusion body myositis.