While mice with a haploinsufficiency mutation in the gene encoding CENP-E, a centromere-linked mitotic checkpoint protein that when defective produces aneuploidy, exhibited higher levels of spontaneous lymphomas and lung tumors, these mice also had lower rates of chemically or genetically induced tumor formation [36], indicating that genomic instability acted both oncogenically and as a tumor suppressor. This evidence concerns the gene CENPE and lymphoma.