UCP1 and obesity due to melanocortin 4 receptor deficiency: Currently, one of the most important focuses and hotspots of obesity treatment is lipid browning.22, 23 Lipid browning could destroy energy homeostasis to consume lipids without producing ATP energy, and UCP1 is the most important marker of lipid browning.24 Immunofluorescence analysis and western blot showed that UCP1 was upregulated in cells stably overexpressing PLCL1 (Figure 2E; Figure 3E,F, Supporting Information), suggesting that lipid browning might take place in these cells.