CXCL12 and neoplasm: Additional factors have been implicated in altering vascular permeability, secreted either locally by tumour cells within the vasculature or systemically from the primary tumour214, to facilitate the alteration of vascular endothelial barriers, including microRNAs (miRs)215, secreted factors such as VEGF, a disintegrin and metalloproteinase domain-containing protein 12 (ADAM12), epiregulin, cyclooxygenase-2, matrix metalloproteinase-1 (MMP-1) and MMP-2216, angiopoietin-like 4217, angiotensin II (ANG-2), MMP-3 and MMP-10218, and finally stromal cell-derived factor 1 (SDF1)219.