STX4 and obesity due to melanocortin 4 receptor deficiency: Global STX4 overexpression (2–5-fold STX4 overexpression detected in skeletal muscle, adipose, and pancreas) extended lifespan by ~35%; underlying this was the retention of youthful insulin sensitivity and GSIS capacity, even in the face of diet-induced obesity stress, indicating an anti-aging role for STX4 beyond conventional exocytosis function [19].