5.1.1. Sample preparation
After seeding the cells and inducing cell death as described in
Section 3.2.2, 270 ll of cells are transferred in suspension from
the 24-well plate to a 5-ml polypropylene round-bottom tube
and combined with 30 ll of 10 PI solution prepared from a
3 mM stock. The tubes are freeze-thawed once by placing them
briefly in liquid nitrogen. This procedure permeabilizes the cells
and stains them with PI. The samples are then analyzed by flow
fluorocytometry.