CREB1 and obesity due to melanocortin 4 receptor deficiency: It was shown that SREBP1 and PPAR-γ belong to the same molecular mechanism and are both activated by the cAMP response element-binding protein (CREB) and CREB-regulated transcription coactivator (CRTC), indicating that the molecular pathway CREB/SREBP1/PPAR-γ significantly contributes to the development of obesity [21].