WIN55212-2 inhibited differentiation of human monocytic U937 cells into an adherent phenotype. Differentiation of U937 cells was induced by 25 nM PMA with or without co-incubation with WIN55212-2. The experimental groups were: 1.) Vehicle control = treatment with 0.1% DMSO only, 2.) Differentiation control = treatment with 25 nM PMA, 3.) Experimental groups were treated additionally with 3 μM or 5 μM WIN55212-2, respectively. Adherent (figure 1a) and non-adherent cells (figure 1b) were separated and quantified after different time points up to 72 h by FACS analysis. Percentage of control group at time point zero is shown. Data are shown as mean +/- SEM, n = 12; *p < 0.05 in comparison with the PMA-treated group without WIN55212-2.