Influence of ST1346 on ATRA-induced surface expression of the NB4 differentiation markers.

(A) NB4 cells were treated for 3 days with vehicle alone, ST1346 (5 μM), ATRA (0.01μM), or the combination of the 2 compounds. Typical flow cytometric profiles following staining of cells with a fluoresceinated anti-CD11b antibody (right graph) and an isotype-matched negative control (left graph) are shown. (B) NB4 cells were treated for 3 days with vehicle alone, ST1346 (5 μM), the indicated concentrations of ATRA (open symbols), or the combination of the 2 compounds (closed symbols). The level of expression of the indicated phenotypic markers was determined by flow cytometry using fluorescein-labeled monoclonal antibodies against CD11b, CD38, and CD14 or irrelevant isotype-matched antibodies (neg). The percentage of marker-positive cells is shown in the left graph, and the amount of cell-associated fluorescence in arbitrary units is illustrated in the right graph. In all cases, cells were seeded at an initial concentration of 200 000/mL. Results are representative of 2 independent experiments.