FIGURE 5.

Substitution of Leu⁸⁵⁷ of JAK3 with different residues can confer receptor-independent constitutive activity. HEK293 cells were transiently transfected either with WT JAK3, or different JAK3 mutants: JAK3^WT, JAK3^V674A, JAK3^L857P, JAK3^L857A, and JAK3^L857E in pMX-IRES-CD4 (A) and JAK3^WT, JAK3^V674A, JAK3^L857P, and JAK3^L857Q (B) in pMSCV-GFP. The STAT5-responsive luciferase reporter pLHRE-luc (firefly luciferase) and the pRLTK plasmid (Renilla luciferase) were co-transfected. 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 means of three different experiments, each performed in triplicate. A Kruskal-Wallis test with Dunn correction was performed to determine p values between the control condition without JAK3 and the WT or mutant forms of JAK3 for each condition. *, p < 0.05; **, p < 0.01; ***, p < 0.001.