To understand biological mechanisms, by which Cdkal1−/− mice could show protection against high fat diet-induced obesity and insulin resistance, we performed microarray gene expression analysis on the muscle, along with comparing mRNA expression of target genes (including several physiological candidate genes) in brown adipose tissues (BAT) and WAT, liver and muscle between Cdkal1+/+and Cdkal1−/− mice (Figure 5). The gene discussed is CDKAL1; the disease is obesity due to melanocortin 4 receptor deficiency.