Description: The 104D2 monoclonal antibody reacts with human CD117, also known as c-Kit , Steel factor receptor and stem cell factor receptor. A member of the tyrosine kinase receptor family, this 145 kDa molecule is expressed by hematopoietic progenitor cell subsets and mast cells. The interaction of c-Kit and Steel factor promotes proliferation and differentiation of hematopoietic progenitor cells and mast cell differentiation. CD117 is also expressed by melanocytes and plays a role in signaling and activation of these cells.