SDC1 and plasma cell leukemia: The role of Sp17 in promoting heparin sulphate-mediated adhesion of lymphoid cells has been proposed by Lacy and Sanderson [23], who showed that Sp17 expressed on the surface of lymphoid-derived cells from a patient with plasma cell leukemia promoted cell-cell adhesion via interaction with the heparin sulphate chain of syndecan 1.