GRK5 and obesity due to melanocortin 4 receptor deficiency: In support of previous work showing a positive correlation between Grk5/GRK5 gene expression and adipose tissue mass in rats [4] and humans [6], we demonstrate here that high fat diet-induced obesity in male mice versus chow-fed lean male mice (Fig. 1A) displayed ~2-fold increased Grk5 mRNA levels in epidydimal visceral white adipose tissue, but not in brown fat (Fig. 1B).