While loss of Necdin did not affect the early apoptosis of leukemia cells expressing MLL-AF9 following 48 hour AraC treatment (Figure 3D), the number of late apoptotic cells (Annexin V+/PI+) was significantly increased in Necdin null group compared with wild type group following high concentration of AraC (0.5 μM) treatment (Figure 3E). This evidence concerns the gene MLLT3 and leukemia.