Cluster of differentiation 24, also known as signal transducer CD24 or heat stable antigen CD24 (HSA), is a mucin-type glycosylphosphatidylinositol-linked glycoprotein expressed on the surface of B-cells, differentiating neuroblasts and many tumors. It is involved in molecular adhesion and metastatic tumor spread and serve as a normal receptor for P-selectin. The CD24 / P-selectin pathway could be important in dissimenating of tumor cells by facilitating the interaction with platelet and endothelial cells. It has also been considered as a tumor marker. High rate of CD24 expressions have been found in epithelial ovarian cancer, breast cancer, non-small cell lung cancer, prostate cancer and pancreatic cancer.