SYK and diffuse large B-cell lymphoma: Whereas STAT3 inactivation has an important role in DCZ3301-induced apoptosis, we investigated the oncogene upstream that induces STAT3 phosphorylation, such as tyrosine kinase Lyn and Syk.16, 22 As shown in Figure 6a, we found that the phosphorylation (Y507) of tyrosine kinase Lyn, rather than Syk, was downregulated by DCZ3301 treatment in DLBCL cells.