Analysis of AID-promoted c-myc/IgH translocations in in vitro stimulated B cells has allowed an accurate measurement of the frequency of these events in AID+/− B cells, as opposed to the IL6tg (this study) or pristane induced plasmacytomas in Bcl-xL mice [36], where the contribution of in vivo selective mechanisms can not be discriminated. This evidence concerns the gene MYC and plasmacytoma.