In the nucleus HuR binds to mRNAs containing adenylate-uridylate rich elements in the T-untranslated region. HuR may influence expression of its ligand mRNA through regulation of polyadenylation, translocation of the message to the cytosol, stabilization of the mRNA and/or altering its translational efficiency. Suppression of HuR using siRNA resulted in an attenuation of the 3T3-L1 differentiation program, consistent with HuR control of the expression of mRNA ligand(s) critical to the differentiation process. In the present study, we begin to identify mRNA ligands of HuR whose regulated expression is necessary for adipogenesis. (C) 2009 Elsevier Inc. All rights reserved.