Simplified model on TCL1-driven neoplastic development of GC B lymphocytes. Elevated levels of TCL1 in GC B cells increase proliferation, resistance to Fas-dependent apoptosis, and expression of AID (not shown). Full malignant transformation of these cells is strictly dependent upon OCA-B, which is required for the development of GCs in secondary lymphoid tissues. TCL1-transgenic lymphomas, classified as FL, BLL, or DLBCL, exhibit features of genomic instability and contain elevated Myc (not shown).