CFU-GM colony formation in MC cultures after an initial 48-hour period of exposure to DT-GM-CSF (100 ng/mL) of 2 normal BM samples. Culture condition 1 was MC supplemented with GM-CSF, G-CSF, IL-3, SF and Epo in 30% FCS; condition 2 is MC supplemented with FCS 30% and GM-CSF only, condition 3 is MC in SFM with GM-CSF only. The number of CFU-GM surviving in DT-GM-CSF containing medium is expressed relative to the number of CFU-GM that survived in the respective “medium only” control group. (□) sample no. 1; (▪) sample no. 2.