Figure 4. UV irradiation and cold shock did not cause flip-over of PS onto cell surface.

(A) B16F10 cells in culture were added aliquots of PI and Annexin V stains, exposed to UV irradiation (480 mJoule/cm²) and cold shock (4°C for 5 min), and subjected to time-lapse imaging at room temperature (2 min per frame). Little or no Annexin V-positive cells were observed. (B) Similarly, B16F10 cells were treated with betulinic acid (100 μM) and subjected to time-lapse imaging at room temperature (2 min per frame).