The CD40-regulated ‘mature B-cell signature’ comprises genes of known importance in DLBCL/BL pathogenesis including NFKB2, MEF2C (Wilker et al, 2008) and TNFAIP genes (Compagno et al, 2009; Kato et al, 2009; Lohr et al, 2012). The gene discussed is MEF2C; the disease is Burkitt lymphoma.