CCL5 and breast cancer: Specifically, this previous study reported that basal breast cancer cells secrete interleukin 6 (IL6), a cytokine, which conditions (educates, reprograms) lymphatic endothelial cells (LEC) within pre-metastatic organs and primary tumors to secrete the chemokine CC-chemokine ligand 5 (CCL5) and the growth factor, vascular endothelial growth factor A (VEGFA)4.