STAT1 and neoplasm: To further investigate STAT1 phosphorylation in the context of the tumor environment, we examined meningioma tumor lysates for the presence of interferon gamma (IFNγ) and tumor-associated macrophages by using CD163 marker staining preferentially M2 macrophages.28 Variable protein levels of IFNγ and CD163 were detected, but there was no evident correlation with STAT1 phosphorylation and no JAK1 phosphorylation was detected (Figure 2A).