CSF2 and melanoma: Since the use of IL-6 alone did not reveal any increase on MDSC frequency or allow to generate suppressive cells (31), and injection of an IL-6 blocking antibody could not reduce MDSC frequencies or an increase in CD8+ T cells in a melanoma model (32), we conclude that GM-CSF is the primary driver of M-MDSC generation and IL-6 fulfills the function of a secondary enhancer.