MMP9 and B-cell chronic lymphocytic leukemia: Moreover, vascularization of the BM is accompanied by the adhesion of CLL cells to the stroma (including ECs, fibroblasts, and macrophages) [68,69,70,71]: both activated stromal cells and activated CLL cells are able to produce VEGF, Ang-2, and MMP-9 [56,57,70,72,73], which in turn can modulate neovascularization in different ways [3,69,70,74,75,76] (Table 1).