Nuclear extracts were prepared from MEL cells (2 × 107) using a kit (Active Motif, Carlsbad, California, United States). The Sox6 in vitro translation expression vector, tagged with c-Myc and HA, was described before [15]. The translation was performed in a reticulocyte lysate based in vitro translational system (TNT® Quick Coupled Transcription/Translation Systems, Promega). A vector without the Sox6 coding sequence was also translated as a negative control.