SREBF1 and obesity due to melanocortin 4 receptor deficiency: SREBP-1c is activated by overnutrition, obesity, inflammation, oxidative stress, endoplasmic reticulum (ER) stress, etc. Our findings demonstrated that farnesoid X receptor (FXR), a member of the nuclear receptor superfamily, could negatively regulate de novo lipogenesis by counteraction against SREBP-1c.