BCL6 and Burkitt lymphoma: The evidence supporting this notion includes: expression of cell surface markers that are consistent with a post-GC cell; the presence of class switched immunoglobulins specific to the model autoantigen, HEL; the presence of point mutations in the BCR that are likely the result of somatic mutation that occurs during the GC reaction; and the detection of high levels of mRNA for two GC-associated genes, Bcl-6 and AID. This is the most complete set of parameters yet used to define a mouse model of BL.