Expression of the FOXP1 transcription factor is strongly associated with inferior survival in patients with diffuse large B-cell lymphoma.

Gene expression profiling studies have reported up-regulated mRNA expression of the FOXP1 forkhead transcription factor in response to normal B-cell activation and high expression in a poor prognosis subtype of diffuse large B-cell lymphoma (DLBCL). The purpose of this study was to investigate the prognostic importance of FOXP1 protein expression in an independent series of DLBCL.First, the specificity of our FOXP1 monoclonal antibody was verified by confirming that it did not recognize the closely related FOXP2, FOXP3, or FOXP4 proteins. FOXP1 protein expression was then analyzed by immunohistochemistry using a DLBCL tissue microarray constructed from 101 previously untreated de novo cases from the British Columbia Cancer Agency. FOXP1 expression was scored as either positive (>30% positive nuclei) or negative (