CSF1 and neoplasm: In addition, inhibition of CSF-1R signaling (which prevented VEGF-A secretion in Fig. 3A) increased intracellular macrophage VEGF-A levels using the same co-culture system (Fig. 3E, F), indicating that the CSF-1/CSF-1R signaling between macrophages and tumor cells induces the release of intracellular VEGF-A from macrophages.