HDAC9 and obesity due to melanocortin 4 receptor deficiency: Therefore, to examine the role of adipocyte-expressed HDAC9 in HFD-induced obesity and metabolic disease, HDAC9 floxed mice were bred with adiponectin-cre mice to generate adipocyte-specific HDAC9 knockout mice (A-KO) on a C57BL/6 background.