VEGFA and neoplasm: It might furthermore be speculated that this might happen not only because of the effect of VEGF itself on rates of superoxide anion radical and peroxynitrite production in the endothelial cells, but also because of other sources of superoxide anion radical that can be converted into peroxynitrite in the tumour microenvironment, which might include not only activated phagocytes, but in a number of cases also the tumour cells themselves.