STAT3 and neoplasm: Importantly, we also showed that treatment of the LMP1-expressing ΔEBNA2 + Myc tumor-derived “B1” cell line (derived from Donor 1) with the Src kinase inhibitor, dasatinib, not only strongly inhibits the level of constitutive STAT3 tyrosine 705 phosphorylation but also decreases LMP1 expression (S8 Fig).