BCR-ABL1+ (GFP+) BP-1+ cells were also reduced in lung (P = 0.05, Fig. 3b), spleen (P = 0.02, Fig. 3c), liver (P = 0.03, Fig. 3d), and meninges (P = 0.02, Figs. 3e, f and S4I) of MMP-9-deficient compared with wild type mice with B-ALL. This evidence concerns the gene MMP9 and acute lymphoblastic leukemia.