STAT-target gene expression induced by IFNα in U1A cells expressing TYK2 variants. Cells were treated with 500 pM IFNα. Total RNA was extracted, reverse-transcribed, and analysed by RT-qPCR for the indicated genes. Values were normalised to GAPDH and are expressed as n-fold versus untreated cells for each variant. Mean values of three independent experiments ± SD are shown. Two-way ANOVA was used for statistical analysis, performing post hoc Bonferroni tests for intergroup differences. * For each variant, comparison between the indicated time and untreated cells; # for each time condition, comparison between each variant and WT. For * and #: * p < 0.05; ** p < 0.01; *** p < 0.001; **** p < 0.0001.