Apoptotic cell death rates of FL cell lines induced by chemotherapeutic agents in the different cell conditions. (A) Cell death rates of FL cell lines induced by etoposide, 4-OHCP, and bendamustine in the absence of feeder cells in the presence of L cells or CD40L⁺ L cells. Caspase-positive and dead cells were assessed by flow cytometry. Error bars represent the SEM of duplicate samples. (B) Cell death rates of FL and MCL cell lines induced by etoposide, 4-OHCP, and bendamustine treatment in the presence of L cells or BAFF⁺ L cells. Caspase-positive and dead cells were assessed by flow cytometry. Error bars represent the SEM of duplicate samples. (C) Ratio of cell death in FL cells cocultured with CD40L⁺ L cells to L cells (left panels), or those cocultured with BAFF⁺ L cells to L cells (right panels), at the indicated concentrations of the chemotherapeutic agents.