Proliferation of the BaF3, 32D, and FDCP1 cell transfectants in response to IL-3, EPO, or G-CSF. The individual cell clones as indicated were incubated in the absence of any growth factor (strongly shaded box), as a negative control, or in the presence of IL-3 (medianly shaded box) or EPO (lightly shaded box) or G-CSF (unshaded box) for 36 to 48 hours. Proliferation was measured by reduction of Alamar Blue, with quantitation of fluorescence by excitation at 530 nm and emission at 590 nm. Error bars indicate the mean and standard deviation for triplicate assay values.