While the actions of extracellular NM23/NDPK shed by breast cancer cells to take advantage of the vascular actions of ATP is, by itself an important contribution to understanding the biology of breast cancer cells, we have recently expanded on our earlier evidence that activation of the endothelial purinergic receptor signaled in an unexpected manner through the vascular endothelial growth factor (VEGF) receptor [67]. The gene discussed is P2RY1; the disease is breast cancer.