CSF1 and breast adenocarcinoma: To initialize phagocytosis, formaldehyde fixed and osmium-stained MDA-231 cells, which are a breast adenocarcinoma line, were added to MDMs polarized with M-CSF, LPS, IFN-γ, or IL4 for 2 hours, an incubation time that appeared reasonable given the high rate of phagocytosis observed for E. coli.