The Liver X Receptor (LXR) and Retinoid X Receptor (RXR) form a dimer together which binds to DNA. Each also has others binding sites specific for other molecules (and each other).
The LXR-RXR dimer regulates expression of host of genes including many involved in cholesterol transport, including ABC transporters, GLUT4, Apoproteins C1, C2, D, and E and Acetyl-CoA carboxylase. When inactivated, normally a corepressor molecule is bound to each LXR and RXR.
Which of the following is NOT typically bound to either LXR or RXR when the dimer is activating transcription of genes?