In diffuse large B-cell lymphoma, REL amplifications are common, being reported in approximately 15% of cases31 and overexpression of c-Rel is also associated with a worse prognosis.32 Other cases of B-cell lymphoma have been reported to be associated with the S525P REL mutation; in-vitro this mutation is more oncogenic than WT REL, but has reduced transcriptional activity.33 This may provide a biologically coherent mechanism to explain the enhanced B-cell lymphoid proliferation induced by H. felis following c-Rel deletion in our model. Here, REL is linked to diffuse large B-cell lymphoma.