CXCL8 and neoplasm: Collectively, we proposed a ‘two-phase’ model that solid endothelial cords firstly penetrated and played a role in stimulating initial tumor cells proliferation in a paracrine manner by releasing endothelium-derived soluble factors (‘angiogenic factor’, e.g. IL-8 and FGF2), followed by lumenization allowing the blood perfusion to supply oxygen and nutrients to support the further tumor growth (Fig. 7J).