We then performed FACS and IHC and found that in lymphoma-free mice at older ages (14–16 months), B220+ cells from p18−/−;Gata3+/− spleens incorporated more BrdU and had a higher percentage of Ki67+ cells (Figure 5E, 5F) than those from age-matched p18−/− cells. The gene discussed is PTPRC; the disease is lymphoma.