The SYK inhibitor, R406, induces apoptosis in a subset of DLBCL cell lines. DLBCL cell lines were cultured with 1 μM or 4 μM of R406 or vehicle alone for 96 hours. Thereafter, cellular apoptosis was assessed using annexin V–FITC/propidium iodide (PI) staining. All of the R406-sensitive cell lines (left panel) were previously designated as “BCR-type” DLBCLs using the cell line transcriptional profiles and a recently described ensemble comprehensive cluster classifier.¹⁴  None of the R406-insensitive cell lines were identified as “BCR-type” (“Other,” right panel).