Percentage of quadrant distribution (QD) in the PI-annexin-V staining apoptosis assay.

The data presented are the mean ± SD of three independent experiments. LL, Lower Left; LR, Lower Right; UL, Upper Left; UR, Upper Right *: P<0.05, **: P<0.01. UR (upper right) indicates the percentage of cells undergoing late apoptosis, i.e., the cell death rate. LR (lower right) indicates the percentage of cells undergoing early apoptosis. * p<0.05 **P<0.01 compared with the control.