A structural alignment with Brd4 BD2 shows that larger Brd4 side chains at four of these contact positions, including signature positions 1,3 and 5 (Trp374, Leu387 and His437) and residue Tyr432 (Fig. 7e,g), reduces the volume available for compound 2, explaining the inability of 2 to inhibit the human BD. This evidence concerns the gene BRD4 and Behcet disease.