AICDA and cancer: However, AID can be transiently expressed in pre-B cells concurrent with RAG expression when pre-B cells are stimulated by cytokines.9 Indeed, examination of the various chromosomal translocations that occur in many lymphoid malignancies show that one DSB was RAG-induced at the IGH locus adjacent to a D or J cassette while the other DSB locus shows evidence of AID activity,10 indicating the most likely mechanism for oncogenesis in a subset of cancers is AID expression in pre-B cells.11