In normal cells, phosphatidylserine (PS) is only distributed inside the lipid bilayer of the cell membrane. In the early stage of apoptosis, the PS in the cell membrane turns from the inside to the outside, exposing the PS to the external environment of the cell. 。Annexin V is a 35-36 kDa Ca2+-dependent phospholipid binding protein with high affinity to PS, so it can bind to the cell membrane of cells in the early stage of apoptosis through the PS exposed outside the cell. Therefore, Annexin V is recognized as an early detection cell One of the sensitive indicators of apoptosis. The Annexin V is labeled with Phycoerythrin (PE). The labeled Annexin V retains a high affinity for PS and can be used as a probe to detect apoptosis using flow cytometry. Since PS valgus occurs in the early stage of apoptosis, Annexin V-PE staining can identify the occurrence of apoptosis in the early stage of apoptosis. 7-Aminoactinomycin (7-AAD) is a nucleic acid dye. 7-AAD cannot penetrate the complete cell membrane of normal cells or early apoptotic cells, but can penetrate membrane-damaged cells such as late apoptotic cells or necrotic cells The cell membrane and the DNA within it can be used to distinguish early apoptotic cells from late apoptotic cells or necrotic cells. Therefore, co-staining Annexin V-PE and 7-AAD can distinguish cells in different stages of apoptosis.   Strong specific staining PE dye is red fluorescence, and can be co-dye with green fluorescence   All components of this kit are stored at 2-8°C. Annexin V-PE and 7-AAD Staining Solution should be stored in the dark and should not be frozen.