CD24 was first described in the early 1980s and only attributed to scattered publications, referred to as a cell surface molecule in hematopoiesis. Recently, studies are accumulating to show that CD24 conveys a function in cell-to-cell interaction and regulation of proliferation and adhesion. CD24 appears to be highly expressed in a large variety of human cancers and to contribute to the acceleration of tumor growth and metastases shedding by binding to platelet (P)-selectin, L1 and by evoking--to date unknown--intracellular signal pathways. Anti-CD24 monoclonal antibodies thus act as a promising cancer treatment as was shown in the setting of gastrointestinal cancers. Recent articles also correlate CD24 expression with the identification of 'tumor stem cells'.