ANXA5 and glioblastoma: The cellular apoptosis and death in the U87-MG GBM cells were categorized into three groups on the basis of the intensity of Annexin V and propidium iodide (PI) fluorescence: early apoptosis (Annexin V–FITC+/PI− quadrant), late apoptosis (Annexin V–FITC+/PI+ quadrant), and cell death (Annexin V–FITC+/PI+ quadrant; Figure 4).