INS and obesity due to melanocortin 4 receptor deficiency: Overexpressing Ntn1 in the mouse gut suppresses intestinal cell apoptosis and promotes tumor development (Mazelin et al., 2004)In mice lacking the low‐density lipoprotein receptor, deleting Ntn1 in macrophages attenuates atherosclerosis (van Gils et al., 2012)In a mouse model of obesity, the hematopoietic deletion of Ntn1 enhances insulin sensitivity and decreases inflammation (Ramkhelawon et al., 2014)