In vitro association properties of CXCL4 and CXCL4L1 to GAGs sulfated membranes. (A) Western blot with Mab-L4 antibody, which neither discriminates between CXCL4, CXCL4L1, or CXCL4-241, of membrane fractions of cells treated with 1 μg/mL recombinant proteins. (B) Schematic representation of membrane retention or diffusion of secreted protein after transfection. (C) CXCL4-ELISA assay on the different fractions of transfected HEK293T cells. CXCL4, CXCL4L1, and CXCL4-241 released in the medium (1) or remaining cell-associated (2), were quantified. (D) Distribution of CXCL4 and CXCL4L1 in medium and the membrane bound or intracellular fraction. Membrane-bound chemokines were collected with high salt (NaCl) or heparinase II (Hep II) treatment. (E) Membrane binding of CXCL4 and CXCL4L1 in cells treated or not with sodium chlorate (NaClO₃). Results are represented as percent of total proteins expressed.