In vitro proliferation of cS5^F-transformed bone marrow cells. Sorted GFP⁺ BM cells from 2 cS5^F-grafted mice (BM1 and BM2) or from 2 control GFPv mice (BM5 and BM6) were cultured in the presence of SCF (10 ng/mL). In addition to SCF, IL-3 (10 ng/mL) was added to BM5- and BM6-cell cultures. Cells were counted daily using the trypan blue dye exclusion method.