CDDO induces granulocytic-monocytic differentiation and phagocytic activity of HL60 cells. (A) Wright-Giemsa stain (top panel) and NBT assay (bottom panel) of HL60 cells after 4 to 5 days of culture. The cells were cultured in the presence of either 0.01% DMSO (vehicle), 1 μM ATRA, or 1 μM CDDO. (B) HL60 cells were cultured in the presence of either 0.01% DMSO, 1 μM ATRA, or 0.1 to 1 μM CDDO for 2 days prior to incubation with FITC-labeled E coli for 1 hour and analyzed for FITC positivity using fluorescence microscopy (top panel) or flow cytometry (bottom panel). The percentage of FITC-positive cells as detected by flow cytometry is indicated.