STAT1 and neoplasm: In agreement with previous reports, ruxolitinib treatment diminished tumor infiltrating CD8+ and CD4+ T cells and significantly lowered NK cell numbers but did not result in tumor metastasis, even in the absence of p53.17, 18, 42 In agreement with others, JAK inhibition abrogated interferon‐γ‐mediated STAT1 signaling and reduced PD‐L1 expression levels.43 Nevertheless, NK and CD8+ T cell activation markers were reduced in lungs of ruxolitinib treated mice.