Calcineurin inhibition triggers cytotoxicity in ABC DLBCL. (A) ABC DLBCL or (B) GCB DLBCL cells lines were treated with DMSO, 300 nM CsA, or 300 nM FK506, and cell numbers were counted every second day as indicated. (C) Annexin V-positive cells were measured by flow cytometry after 4 days of DMSO, CsA, or FK506 treatment. (D) GCB (BJAB and HT) and ABC (HBL-1, TMD8, OCI-Ly10, U2932) DLBCL cell lines were treated with DMSO, CsA, or FK506 for 4 days and caspase activity was determined using DEVD-AMC as substrate. (E) Cell count of MCL cell lines treated with either DMSO or 300 nM CsA as indicated. (A-E) Cell counts, frequency of cells, or caspase activity were normalized to the solvent control. Error bars correspond to the mean ± SD. Statistical significance was calculated using Student t test (*P < .05, **P < .01, ***P < .001). Data are representative of at least 3 (A-C,E) or 2 (D) independent experiments. d, days; DMSO, dimethyl sulfoxide; SD, standard deviation.