Upregulation of cMyc correlates with IL-21–induced direct cell death in MCL cells. (A) Immunoblotting for cMyc in IL-21–sensitive (Mino, HBL-2, SP-53, and specimen 1) and resistant (Jeko-1, G-519, L-128, and specimen 4) MCL cell lines and primary tumors treated with 100 ng/mL IL-21 for 24 hours. cMyc protein levels quantified by densitometric analysis are displayed below each panel. (B) Mino cells transfected with cMyc siRNA, and (C) L-128 and G-519 cells transfected with pcDNA3-cMyc plasmid were treated at 24 hours posttransfections with IL-21 (100 ng/mL). Percentage of cell death was quantified using flow cytometry at 48 hours posttreatment. Immunoblotting for cMyc at 24 hours posttransfection were performed to confirm knockdown or overexpression of cMyc. Results in panels A-C are representative of 3 independent experiments. GAPDH and actin served as loading controls. *P < .05; ***P < .005.