To determine whether enforced transgenic expression of BCL2 and IL6 acts synergistically with loss of activation-induced cytidine deaminase (AID) to promote the expansion and malignant transformation of IgM-producing B lymphocytes, AID-deficient BALB/c (C) BCL2+IL6+AID− mice were monitored at weekly intervals for signs of tumor development, such as declining health status parameters and peripheral lymph node enlargements (Figure 1a). This evidence concerns the gene BCL2 and neoplasm.