A blunted response of IL-7-treated LICs to dasatinib is reversed by ruxolitinib. (A) LICs were treated with the indicated concentrations of dasatinib, with or without 10 ng/mL of IL-7 and 100 nM ruxolitinib. Cell viability was assessed 72 hours later using a nonradioactive cell viability assay. The calculated inhibitory concentration required to arrest 50% of the cells (IC₅₀) values and results shown are taken from 3 separate experiments, each yielding triplicate determinations for each data point. Notably, the IC₅₀ of dasatinib is augmented ∼20-fold by IL-7 addition and is completely reversed by ruxolitinib. (B) Cells were cultured for 8 hours in the presence of vehicle (DMSO), 1 nM dasatinib, 100 nM ruxolitinib, or both drugs, either in the presence (+) or absence (−) of IL-7. Cells were lysed, and equal amounts of protein loaded per lane were resolved on denaturing gels and immunoblotted with antibodies to phosphorylated (P) and total STAT5 and STAT3. Dasa, dasatinib; DMSO, dimethylsulfoxide; Rux, ruxolitinib.