PRDM16 and obesity due to melanocortin 4 receptor deficiency: Such findings were confirmed by others showing that metformin is possibly taken up by BAT cells [31], and its short-term treatment (duration equivalent to 2 weeks or less) is consistent with the enhanced cellular oxygen capacity of BAT or the elevated expression of its thermogenic transcriptional factors such as Prdm16 and UCP1 in preclinical models of obesity [32,105], further implying that the anti-obesity properties of metformin are likely modulated through its capacity to enhance BAT thermogenic activity.