To elucidate the role of WTAP in the development of obesity, we generated a macrophage-specific Wtap knockout mouse model by crossing the Wtapf/f mice with the LysM-Cre mice (the resulting LysM-Cre Wtapf/f mice were defined as KO thereafter), and their Wtapf/f littermates were served as controls (Fig. 2A). Here, WTAP is linked to obesity due to melanocortin 4 receptor deficiency.