Biological activity of sIL-11R on M1/IL-11R cells. ³H-thymidine incorporation (1 μCi/well) measuring (A) IL-11 dose response in the presence of saline (□) or 40 nmol/L sIL-11R (▪) or (B) sIL-11R dose response in the presence of 20 pmol/L IL-11 (•) or 25 U/mL LIF (○). (C) Effect of sIL-11R on colony formation in agar cultures. Shaded region of bar represents the number of differentiated colonies. Three hundred cells added/plate. Results expressed as the mean and standard deviation of duplicate cultures from 2 independent experiments.