Effect of filamin knockdown on β2 integrin–dependent T-cell adhesion to coated ICAM-1. (A) Jurkat T cells were transfected with siGENOME SMART pool human filamin A (FLNa) siRNAs or control siRNAs. Filamin knockdown with filamin-specific siRNAs, but not control siRNAs, resulted in knockdown of filamin protein levels, as shown by Western blotting of corresponding cell extracts with antifilamin antibodies. The blot was stripped and reprobed with actin antibodies to show equal loading. (B) siRNA-transfected cells were left untreated or stimulated with 200 nM PDBu and cell binding to coated ICAM-1 was assayed for as described in “Adhesion assay.” Treatment of cells with FLNa siRNAs, but not control siRNAs, increased the stimulated cell binding to ICAM-1 (P < .05 for PDBu-stimulated samples). The experiment was repeated 9 times with similar results. Error bars represent SD.