Cayman’s Cell Cycle Phase Determination provides an easy to use tool for studying the induction and inhibition of cell cycle progression in any cell suspension sample. The assay involves the fixation and permeabilization of the cells of interest, making possible the staining of DNA within intact cells by propidium iodide. This kit will allow the investigator to determine the percentage of cells in a given sample that are within G1/G0, G2, or S phase at the time of fixation, as well as to quantify cells in the sub-G1 phase prior to apoptosis by FC.