After completion of treatment time, discard the used up media from plates/flasks, add trypsin to detach the cells. Collect in tubes by centrifugation, discard the supernatant, add Annexin V Fitc antibody and PI amde up in provided buffer in kit or add in 1 X PBS (100 microlitre) (2.5microlitre + 5 microlitre for BD Kit), incubate for 20 minutes, add 400 microlitre of Buffer or PBS. Analyse by flow cytometry quickly, without loosing time.