Cell Cycle Assay Kit is designed to monitor cell cycle progression and proliferation by using our proprietary Nuclear Red CCS1 in fixed cells. The dye passes through a permeabilized membrane and intercalates into cellular DNA. The signal intensity of Nuclear Red CCS1 is directly proportional to DNA content after RNA is degraded by RNase provided in the kit. The percentage of cells in a given sample that are in G0/G1, S and G2/M phases, as well as the cells in the sub-G1 phase prior to apoptosis can be monitored with a flow cytometer at Ex/Em = 490/620 nm.