Differentiation of Ba/F3 cells requires the cytoplasmic pairing of two signal transducing receptor chains. (A) RNA (15 μg) from Ba/F3 cells bearing the indicated receptors was analyzed as described in Fig 2. Cell lines and cytokines used for growth are indicated above each lane. β-Globin and GAPDH signals are shown with closed arrowheads. Abbreviations are as in Figure 3B. (B) β-Globin expression in IL-3 or GM-CSF (Ba/F3-GMa/β_IL3 ) or in IL-3 and IL-5 (Ba/F3-IL-5a/β_IL3 ). Ba/F3 cells and Ba/F3-EpoR cells are used as a negative and positive control, respectively.