In most cases a t(12;15) or other myc gene rearrangements could be identified, while double Tg Eμ-myc and Eμ-v-abl presented with an accelerated plasmacytoma onset (5-8 wks for double Tg as compared to 11-52 in Eμ-v-abl), thus confirming the putative role of c-MYC in MM pathophysiology. This evidence concerns the gene ABL1 and plasmacytoma.