Chronic active Epstein-Barr virus infection (CAEBV) is an inflammatory disorder with potential for tumor development. Here, unusual phosphorylation was observed on STAT3 in EBV-infected T- or NK-cells from patients with CAEBV. Researchers found that ruxolitinib, a drug that is currently used for treatment of myelofibrosis and polycythemia vera, could suppress the survival of these EBV-infected cells in a dose-dependent manner, and that STAT3 could be an important new target for treatment of CAEBV.