Sca-1 stands for "Stem cells antigen-1" (official gene symbol: Ly6a). It consist of 18-kDa mouse glycosyl phosphatidylinositol-anchored cell surface protein (GPI-AP) of the LY6 gene family. It is the common biological marker used to identify hematopoitic stem cell (HSC) along with other markers. Sca-1 has a regenerative role in cardiac repair: Host cells with specific Sca-1+CD31− markers arise upon myocardial infarction, with evidence of expression of Sca-1 protein. Sca-1 plays a role in hematopoietic progenitor/stem cell lineage fate and c-kit expression. Sca-1+ HSCs can be found in the adult bone marrow, fetal liver and mobilized peripheral blood and spleen within the adult animal. An anti-Sca-1 Ab is frequently used in combination with negative selection for expression of a number of cell surface markers characteristic of differentiated cells of hematolymphoid lineages (Lin-) to identify and isolate murine HSCs.