α4β1 integrin and CXCL12 independently enhance MMP-9 production in B-CLL cells. (A) B-CLL cells from 4 different patients were added to BSA- or FN-H89–coated wells and in the presence or absence of 150 ng/mL CXCL12. After 24 hours, MMP-9 secretion was analyzed by gelatin zymography and quantitated. Basal MMP-9 levels of cells on BSA and without CXCL12 were normalized to 100. (B) B-CLL cells from 2 patients were incubated on FN-H89 in the presence or absence (None) of the indicated kinase inhibitors. CXCL12 (150 ng/mL) was also added to the cells. Control cells (Contr) were incubated in 0.5% BSA and without CXCL12. The conditioned media were collected after 24 hours and MMP-9 was quantitated. Basal values were normalized to 100. * P < .05; ** P < .01.