May regulate lifespan in response to food availability and oxidative stress. Up-regulated when diet is restricted. Reduced lifespan when diet is restricted, and in the presence of the oxidative stress inducer paraquat (PubMed:19783783). Increased pha-4 and cup-4 expression when diet is restricted (PubMed:19783783). RNAi-mediated knockdown reduces lifespan and resistance to the oxidative stress inducer paraquat (PubMed:19627265, PubMed:19783783). RNAi-mediated knockdown in an eat-2 mutant background rescues lifespan, but lifespan remains greater than in wild-type (PubMed:19783783).