To show the apoptosis inducing effects by Tan-I in monocytic leukemia U937 TPH-1 and SHI 1 cells, 1 × 106 cells were harvested after treatment by different concentrations of Tan-I for 48 h, then stained by PI and annexin V and analyzed by FCM. This evidence concerns the gene ANXA5 and monocytic leukemia.