Effect of β1 integrin subunit or CD44 gene silencing on B-CLL cell membrane-bound and secreted proMMP-9. (A) B-CLL cells were transfected with control or β1 siRNA and analyzed by flow cytometry. Shaded areas represent β1 siRNA-cells; dotted lines, control siRNA cells; and continuous lines, untransfected cells. Representative results from 2 samples of the 3 studied are shown. (B) Gelatin zymographic analysis of proMMP-9 on the membrane fraction and the conditioned media of untransfected or siRNA-transfected B-CLL cells. β1₁ and β1₂ indicate the 2 different β1 siRNAs used. Ctl indicates control siRNA. Values represent the average of the 3 samples after normalizing the proMMP-9 levels of untransfected cells to 100. (C) Flow cytometric analysis of B-CLL cells (shown for 2 samples) transfected with control or CD44 siRNA. Line codes are as in panel A. (D) Gelatin zymography of proMMP-9 on the membrane fraction and the conditioned media of untransfected or siRNA-transfected B-CLL cells. CD44₁ and CD44₂ indicate the 2 different CD44 siRNAs used. Values represent the average of all 3 patients after normalizing proMMP-9 levels in untransfected cells to 100. *P ≤ .05; **P ≤ .01.