Regarding in vivo studies, the knockout of ABCA1/G1 enhances macrophage inflammatory responses (7, 8, 9), and the tissue-specific knockout of ABCA1/G1 or ABCA1 has characteristic effects, including autoimmune activation in dendritic cells (10), impaired diet-induced obesity in adipose tissue (11), and less phagocytosis in astrocytes (12). Here, ABCA1 is linked to obesity due to melanocortin 4 receptor deficiency.