FIGURE 5.

Suppression of VLA-4 expression by RNA interference abrogates acceleration of the hemin-stimulated erythroid differentiation in response to TNIIIA2. K562 cells were transfected with control siRNA or integrin α4 siRNA, as described under “Experimental Procedures.” Cells untransfected (none) or transfected with control siRNA or with integrin α4 siRNA were then stimulated for 2 days with hemin (50 μm) alone or hemin plus TNIIIA2 (50 μg/ml), as indicated. A, aliquots of cell suspensions were examined for erythroid differentiation, as described under “Experimental Procedures.” B, other aliquots were subjected to flow cytometric analysis for the detection of α4 expression. Data represent the mean ± S.E. of triplicate determinations. One of three individual experiments is shown. p < 0.01 compared with control.