CD40LG and plasmacytoma: We have recently shown that heterozygous transgenic iMycEμ mice that carry one mutated and one normal Igh locus are prone to mature B cell and plasma cell neoplasms including IgM+ lymphoblastic B-cell lymphoma (LBL), Bcl-6+ diffuse large B cell lymphoma, and Ig-secreting CD138+ plasmacytoma (PCT) [19].