AG490 treatment reduced STAT3 activation, triggered cell-cycle arrest and apoptosis in ABC-DLBCL cells. (A) Western blot analysis showed that AG490 treatment inhibited STAT3 activation but not Erk1/2 in Ly10 cells. Cells were treated with the indicated drug concentrations and sampled at the indicated time points. Similar results were obtained from Ly3 cells (not shown). (B) MTT assays indicated that AG490 selectively reduced cell growth of ABC-type DLBCL cells (Ly3 and Ly10) without affecting GCB-DLBCL cells (Ly1 and Ly7). (C) Cell-cycle profiles of AG490-treated Ly10 cells were analyzed by PI staining followed by flow cytometry. Cells were treated with the indicated drug concentrations and sampled at the indicated time points. Result shown is representative of 2 independent experiments. (D) Annexin V and 7-AAD staining was used to monitor ongoing apoptosis in Ly1, SUDHL6, Ly3, and Ly10 cells treated for 24 hours with 10 or 20 μM AG490. The percentage of annexin V⁺7-AAD⁻ cells is plotted in the graph.