IRF4 and diffuse large B-cell lymphoma: Cd19Cre/wt;Myd88p.L252P/wt;Rosa26LSL.BCL2.IRES.GFP/wt animals almost uniformly succumbed to clonal lymphoma (penetrance of 83%), which displayed morphological features of DLBCL and stained positive for IRF4 and CD138, while being negative for B220 and BCL6, consistent with a plasmablastic, rather than a classical DLBCL phenotype (126).