To investigate PIM1's relevance in B‐cell activation, PIM1 was inhibited via pharmacologic or genetic ablation in ABC‐ or GCB‐DLBCL cell lines, including those genetically classified as MCD B‐cell lines, with or without BCR stimulation (i.e., +/− anti‐IgM treatment). The gene discussed is CD40LG; the disease is diffuse large B-cell lymphoma.