Fig. 2. The role of insulin/IGF-1 signaling in C. elegans physiology and age-related disease models. Insulin/IGF-1 signaling (IIS) regulates dauer formation, stress resistance, and the models of age-related diseases in C. elegans. Reduced IIS promotes dauer formation and enhances resistance to various external and internal stresses, and pathogens. Inhibition of IIS also ameliorates defects associated with various human disease models. These protective effects of reduced IIS contribute to organismal longevity.