AZD6244 induces caspase-dependent apoptosis. (A) All cell lines were treated with the indicated concentrations of AZD6244 for 18 hours. Protein levels were measured by immunoblotting using specific antibodies. (B) Caspase and PARP cleavage in PBMCs from a DLBCL patient. These results are representative of 3 total DLBCL patients. Cells were incubated with the indicated concentrations of AZD6244 for 6 and 16 hours. Cell lysates was subjected to Western blotting using caspase and PARP antibodies. (C) OCI-LY3 and (D) SUDHL6 cells were preincubated with 50μM caspase inhibitor for 2 hours followed by incubation with 200nM or 300nM for 48 hours. Apoptosis was determined by annexin V/PI staining followed by flow cytometric analysis.