Mice lacking the insulin receptor substrate are more resistant to aging than normal mice, according to University College London researchers. The finding further confirms the link between insulin signaling pathways and aging, and may have implications on aging in humans.In the study, mice were engineered to lack either insulin receptor substrate IRS-1 or IRS-2, both proteins that are activated by the hormone insulin, which regulates glucose and fat metabolism. Compared with normal mice, the mice lacking IRS-1 had: