Ruxolitinib treatment inhibits STAT1-dependent gene expression in splenic CD8⁺ T cells from LCMV-infected Prf1^−/− mice. TCRβ⁺ CD8⁺CD44⁺ T cells were sort-purified from the spleens of uninfected untreated (PBS), uninfected ruxolitinib-treated (Ruxo), LCMV-infected (LCMV), and LCMV-infected ruxolitinib-treated (LCMV, Ruxo) Prf1^−∕− mice. Sorted T cells were used to isolate RNA and complete complementary DNA microarray analysis. (A) PCA of the unfiltered data set. Each dot represents 1 mouse within each cohort. (B) Unsupervised hierarchical clustering of probe sets filtered on a log2 expression difference of >1.5 (1035 total probe sets). The height of the branches in the dendrogram reflects the distances between samples. Probe sets in green represent upregulated genes, compared with the mean expression; red represents downregulated genes.