Proliferation of Ba/F3-GMRαβ-WT, Ba/F3-GMRαβ-F₈ , and Ba/F3-Lx (GMR-α chain alone) cells in response to 10 ng/mL GM-CSF (A) or 1 ng/mL (C). Viability (trypan blue exclusion) was monitored in the same cell lines cultured with 10 ng/mL GM-CSF (B) or 1 ng/mL (D) in the presence and absence of FCS (10% vol/vol) as indicated.