SIM1 and obesity due to melanocortin 4 receptor deficiency: Using a homozygous Rai1 conditional knockout (Rai1-cKO) mice, we found that Rai1 deletion in either subcortical excitatory neurons (vGlut2+) or single-minded homolog 1 (Sim1+) neurons induced obesity in mice (Huang et al., 2016).