Annexin V (ANXA5) is a multifunctional protein that is highly expressed on the apical surfaces of syncytiotrophoblasts, and plays an important role in haemostatic regulations, maintaining blood fluidity of the placenta. Lower ANXA5 levels have been observed in M2/ANXA5 haplotype carrying chorion. The association found between the maternal carriage of the M2/ANXA5 haplotype and an elevated risk of IUGR and/or PE supports the hypothesis that carrier status of this haplotype and the consequently reduced placental ANXA5 expression might be responsible, at least partially, for the onset of these gestational vascular complications. Annexin V is a calcium-dependent phospholipid binding protein that can be used to bind Phosphatidylserine (PS) during an early apoptosis event where the PS becomes exposed at the cell surface. Jurkat cells were treated with 10 uM camptothecin for 4h, 2*105 cells which were resuspended in binding buffer were stained with 5 ug recombinant human Annexin V-FITC and 10 ul Propidium iodide (PI) for 20min in dark room temperature. The flow cytometry was used to detect the early apoptotic and late apoptotic of camptothecin-treated Jurkat cells (Figure 2), the combination of Annexin V-FITC and propidium iodide allows for the distinction between early apoptotic cells (Annexin V-FITC positive and propidium iodide negative), late apoptotic and/or necrotic cells (Annexin V-FITC and propidium iodide positive), and viable cells (unstained). Thus, the recombinant human Annexin V-FITC can bind Phosphatidylserine (PS) at early apoptosis of Jurkat.