CSF2 and neoplasm: Knockdown of GM-CSF in tumor cell lines has been shown to alter the subsets distribution of Gr-1+CD11b+ myeloid cells when implanted in mice, mainly reducing the Gr-1low and Gr-1int populations which are the most suppressive in these models.26 Here, we show that GM-CSF is produced in vivo in CAC that is characterized by the prominent infiltration of suppressive Gr-1+CD11b+ cells.