MMP9 and neoplasm: In addition to promoting pericyte recruitment, gelatinase B/MMP-9 also promotes the recruitment of pro-angiogenic monocytes and CD34+ endothelial cell progenitors, which express VE-cadherin and VEGFR2, to tumours, markedly influencing angiogenesis [252,260,261,262,263] and induces the release of circulating endothelial precursor stem cells from the bone marrow by degrading c-kit ligand, contributing to both angiogenesis and vasculogenesis [90].