Soft agar colony assaying of WEHI-3B D⁺cells expressing LIFR mutants. Cells expressing the various chimeric receptors (W238, T149, T129, T119, F3, F4, F5, or F3/4/5/6) were cultured in agar with increasing concentrations of hGM-CSF or IL-6 (100 ng/mL). The colony numbers (left panels) and the proportions of colonies containing differentiated cells (right panels) were determined after 7 days. The means of duplicate assays are shown.