Inability of GMR-α to signal differentiation is not caused by clonal restriction. Clone 22 (Cl 22), a Ba/F3 clone that expresses the EpoR ectopically was transfected with GMR-α cDNA (Cl 22-GMR-α). After selection in GM-CSF, cells were replated in IL-3, GM-CSF, and Epo, respectively. RNA was obtained and hybridized with a β-globin probe as described. Cytokines used to grow cells are indicated above each lane.