The transplantation of numb⁰³²³⁵ larval neuroblast clones into the abdomen of adult hosts causes tumor growth, with clones growing to 100 times their original size thereby severely damaging and displacing the host's organs. When these tumors are cut into pieces and replanted into new hosts, more than 90% of flies develop tumors. Although genome stability is not grossly affected shortly after transplantation, 40-day-old tumors show karyotype defects such as segmental aneuploidy. Additionally, 15-20% of cells within the tumors have supernumerary centrosomes and these cells tend to be hyperploid.