Furthermore, Zhang and co-workers found that, in the B16F10 melanoma model, monocyte like M-MDSCs were expanded in the circulation and lung and simultaneously released MMP-9 to promote PMN formation130, however, it was also shown that melanoma-derived secretions stimulated Ly6Clow patrol monocytes (PMo) in the bone marrow, and subsequently recruited NK cells and macrophages through PMo to kill melanoma cells in a TRAIL dependent manner. This evidence concerns the gene MMP9 and melanoma.