ALDH1A1 and neoplasm: Importantly, the high ALDH1A1 expression confers to MCF-7 a proangiogenic phenotype mediated by increased VEGF expression and release, and in endothelial cells co-cultured with MCF-7 tumor cells, the release of VEGF induces an angiogenic response, measured as endothelial proliferation, migration, tube formation and permeability.