IBTK and lymphoma: Ibtk+/+Eμ-myc mice developed 60% pre-B lymphoma (B220+IgM−IgD−), 35% mature B lymphoma (B220+IgM+IgD+), and 5% pre-B/B lymphomas (Table 1), which was consistent with the tumor immunophenotype reported by previous studies [13,23,24].