Id1i, pimozide, induces the apoptosis of leukemia cells and prolongs the survival time of AE9a leukemia mice. (A) Id1i (8 μM) treatment downregulates Id1 expression and the level of phosphorylated AKT1 in Kasumi-1 cells (left panel) and AE9a cells (right panel). (B) Id1i (8 μM) treatment induces the apoptosis of Kasumi-1 (left panel) and AE9a (right panel) cells at 48 hours, based on Annexin-V/7-AAD staining. (C) AE9a leukemia mice were treated with Id1i (7.5 mg/kg) or vehicle control for 2 weeks, beginning on day 3. More myeloid cells circulating are found in the peripheral blood of AE9a mice in the control group compared with the Id1i treatment group 5 weeks after transplantation. (D) Id1i (7.5 mg/kg) in vivo treatment prolongs the survival of the recipient mice transplanted with AE9a leukemia cells (53 days vs 40 days, n = 10 for each group, P < .001). (E and F) The frequencies of GFP⁺ and C-Kit⁺ Mac-1 cells in the peripheral blood of AE9a mice in the control or Id1i treatment group were examined 6 weeks after transplantation (n = 10, **P < .01, *P < .05).