CD43 or leukosialin or sialophorin, is predominant cell surface sialoprotein of leukocytes which regulates multiple T-cell functions, including T-cell activation, proliferation, differentiation, trafficking and migration. In hematopathology, CD43 is often considered as a T-cell associated marker, because it is expressed by over 95% of thymocytes and peripheral blood T cells. CD43 positively regulates T-cell trafficking to lymph-nodes via its association with ERM proteins (EZR, RDX and MSN).