Comment on "Brain IRS2 Signaling Coordinates Life Span and Nutrient Homeostasis"

Taguchi et al . (Reports, 20 July 2007, p. 369) reported that mice heterozygous for a null mutation in insulin receptor substrate–2 (Irs2) display a 17% increase in median life span. However, using the same mouse model, we find no evidence for life-span extension and suggest that the findings of Taguchi et al . were due to atypical life-span profiles in their study animals.