A recent report showed that mice with coincident loss of Dok-1, Dok-2 and Dok-3 genes develop highly invasive and transplantable histiocytic sarcoma endogenously, and Dok-1/2/3−/− macrophages demonstrate enhanced proliferation ability [37], suggesting origination of the disease in monocytic cells. The gene discussed is DOK3; the disease is histiocytic sarcoma.