This apoptosis staining and detection kit is used for the combined detection of early-stage cell apoptosis (using Annexin V) and late-stage cell apoptosis or necrosis (using both Annexin V and 7-AAD). It includes Annexin V (Catalog #100-0329 or Catalog #100-0331 or Catalog #100-0333), Annexin V Binding Buffer (Catalog #100-0334), and 7-AAD (Catalog #75001). Annexin V belongs to the Annexin family of intracellular proteins that bind to membrane phospholipids in a calcium-dependent manner. This dye has a high affinity for phosphatidylserine (PS) that is present in the inner leaflet of the plasma membrane. During early-stage cell apoptosis, PS is translocated from the inner to the outer leaflet of the cell membrane, exposing it to the external environment, where it is detected by Annexin V. Visit STEMCELL.com for more information and related products.