Results of these studies provided further evidence that, in primary human AML cells, the high molecular weight E-selectin-binding glycoprotein long assumed to be solely comprised of homodimeric CLA, is, predominantly, CD45, and that expression of this novel E-selectin ligand is characteristic of human AML (Fig. 1, B and C). The gene discussed is PTPRC; the disease is acute myeloid leukemia.