Besides, SIRT7 deficiency increases the levels of activating transcription factor 4 (ATF4) mRNA and enhanced fibroblast growth factor 21 (FGF21) expression, thus protecting against aging-associated glucose intolerance and extending lifespan in male mice, indicating that SIRT7 may play opposite roles in aging to those directed by SIRT1 and SIRT6 (141). This evidence concerns the gene FGF21 and Glucose intolerance.