CXCL12 and neoplasm: Thus, it seems plausible that the production and release of cytokines, chemokines and proteolytic enzymes (VEGF, SDF-1 and metalloproteases) by the lung tumour tissue will increase the mobilisation of CD133+/HPCs from the bone marrow, which may be home to hypoxic tumour tissue and have a fundamental role in tumour neovascularization and progression (Kerbel, 2008; Shojaei and Ferrara, 2008).