To determine whether tumor cells signal through CSF-1/CSF-1R to elicit secretion of VEGF-A from TMEM doorway macrophages and set off the cascade of events leading to TMEM doorway opening and tumor cell dissemination in vivo, we utilized a human-specific CSF-1 blocking antibody in a PDX model of breast cancer. The gene discussed is CSF1R; the disease is neoplasm.