FLT1 and neoplasm: In theory, this does not only inhibit VEGF effects that are mediated via VEGF-R2 on endothelial cells (Figure 1) but also inhibits other signals that are mediated by other VEGF receptors, such as VEGF-R1 on endothelial cells, or other cells of the tumor microenvironment like tumor-infiltrating immune cells like macrophages or monocytes.