Oxidative stress adaptation with acute, chronic, and repeated stress

► H2O2 adaptation involves increased proteolytic capacity in mammalian cells and flies. ► Increased proteasome expression largely explains increased proteolytic capacity. ► Repeated or chronic H2O2 exposure must be at low doses for effective adaptation. ► Repeated H2O2 treatments hinder adaptation unless recovery periods are increased. ► Either repeated or chronic oxidative stress adaptation decreases life span of flies.