PEP005 synergizes with ATRA to induce CD11b expression. Of the lines, 4 were treated with 10 nM ATRA and 20 nM PEP005, alone or in combination, and differentiation was determined after 5 days. Data are mean ± SD of 3 experiments. ^*P < .05; ^**P < .01; and ^***P < .001 for data compared with ATRA alone.