ANGPT2 and B-cell chronic lymphocytic leukemia: For instance, the interaction between CLL cells and BM fibroblasts induces VEGF upregulation and TSP-1 downregulation in CLL cells [68,69]; both CLL-derived VEGF and Ang-2 increase EC tube formation in vitro [74]; and MMP-9 produced by CLL cells and stromal macrophages increases VEGF production by CLL cells, which enhances EC proliferation [70].