FIGURE 9.

Cells expressing JAK3 V674A, L857P, and L857P/Y100A mutants are sensitive to tofacitinib. A, autonomous Ba/F3 cells stably transduced with ALL-associated JAK3 mutants (V674A and L857P) and double mutant (L857P/Y100A) or BCR-ABL as a control were treated with increasing concentrations of JAK1/JAK3 inhibitor tofacitinib (0–3 μm). After 72 h, tritiated thymidine incorporation was measured. The results are means ± standard deviation of three different experiments, each performed in triplicate, represented as percentages of the proliferation of the respective untreated cells. B, HEK293 cells were transiently co-transfected either with JAK3^V674A or JAK3^L857P/Y100A, with a receptor complex (Rec = γc, IL-9Rα, and JAK1^WT), in addition to the STAT5-responsive luciferase reporter pLHRE-luc (firefly luciferase) and the pRLTK plasmid (Renilla luciferase) as transfection control. Cells were treated with tofacitinib (0.5 μm). 24 h post-transfection, the cells were subjected to a luciferase assay. The relative luciferase activity corresponds to the firefly luciferase light emission values divided by the Renilla luciferase light emission values. The results are means ± standard deviation of three different experiments, each performed in triplicate. A Kruskal-Wallis test with Dunn correction was performed to determine p values. *, p < 0.05.