SREBP (Sterol Regulatory Element Binding Protein) 1 and 2 are transcription factors th at regulates cholesterol homeostasis. SREBP proteins are attached to the endoplasmic reticulum and nuclear envelope. SREBP proteins undergo proteolytic cleavage in response to conditions of low cellular sterol. Upon activation of SREBP 1, a soluble NH2 cleavage fragment translocate to the nucleus and activates transcription of enzymes and other proteins required for cholesterol synthesis.