Flow cytometry: 1X10^6 K-562 cells (negative control,left) and MDA-MB-231 cells (right) were surface-stained with ABflo® 488 Rabbit anti-Human PD-L1/CD274 mAb (A22304,2 μg/mL,orange line) or ABflo® 488 Rabbit IgG isotype control (A22069,2 μg/mL,blue line). Non-fluorescently stained cells was used as blank control (red line).