Soft agar colony assaying of WEHI-3B D⁺cells expressing LIFR and dominant negative STAT3. Cells expressing LIFR (W238) and ▵STAT3, or LIFR alone (Pur^rNeo^r) 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.