IFNG and hydrops fetalis: Immunostaining analysis in irradiated WT mouse skin also showed that IR‐induced STAT3 phosphorylation localized primarily to keratinocytes within degenerating HF and IFE cells in regions of acanthosis and was substantially blocked by topical application of small‐molecule JAK inhibitors, ruxolitinib, and tofacitinib (Fig 3B and C), which have been reported to help prevent hair loss in IFN‐γ‐mediated alopecia areata in humans (Xing et al, 2014).