Determining cell cycle stages by flow cytometry

This unit describes assays used to determine the distribution of a population of cells to the different stages of the cell cycle as analyzed by flow cytometry. Staining the DNA with different fluorescent dyes, propidium iodide or DAPI, is one of the most direct ways of staging the cells based on DNA content. These staining procedures can be used with fixed cells or detergent-permeabilized cells. Alternatively, live cells can be stained with the membrane-permeable stain, Hoechst 33242, and sorted on the basis of DNA content for further culture and characterization. When DNA content measurements are coupled with immunostaining for cyclin expression, it is possible to reliably detect even more stages in progression through the cell cycle.