Different pattern of MMP secretion by precursor-B ALL and CB CD34⁺ cells. CB CD34⁺ and precursor-B ALL cells were cultured for 40 hours with or without SDF-1. The presence of MMP-2 and MMP-9 in the conditioned media was detected by gelatin zymography. Conditioned media from HT-1080 cells secreting both MMP-2 and MMP-9 served as control. A representative of 3 independent experiments conducted is shown.