Deficiency of Src family kinases (SFKs) in bone marrow (BM) cells results in different responses to cytokines. Low-density BM (LDBM) cells from wild-type (WT) or SFK−/− mice were harvested and subjected to methylcellulose assay. (A) 3 × 104 LDBM cells were grown in methylcellulose in the presence of granulocyte colony-stimulated factor (G-CSF; 25 ng/mL), granulocyte macrophage colony-stimulating factor (GM-CSF; 50 ng/mL), interleukin (IL)-3 (10 ng/mL), stem cell factor (SCF; 50 ng/mL), or a combination of five cytokines (erythropoietin 2 U/mL, G-CSF, SCF, IL-3, and GM-CSF). Colony-forming units in culture (CFU-Cs) were scored 7 to 10 days later. Bars represent the mean number of CFU-Cs ± standard deviation (SD) at various doses and in the presence of different cytokines. *p < 0.05 compared with WT; **p < 0.05 compared with WT. (B) 1.5 × 104 LDBM cells were grown in methyl-cellulose in the presence of indicated concentrations of G-CSF, GM-CSF, and M-CSF. CFU-Cs were scored 7 to 10 days later. Bars represent the mean number of CFU-Cs ± SD at the indicated doses in the presence of different cytokines. *p < 0.05 compared to WT.