CD43 is a functional E-selectin ligand on human CD34⁺ cells but not on mouse LSK cells. Blot rolling assays were performed on immunoprecipitates of CD44, CD43, and PSGL-1 from human CD34⁺ and mouse LSK cells, and from KG1a cells. In each case, immunoprecipitated protein was resolved by SDS-PAGE and blotted for HECA-452 reactivity. CHO-E cells were perfused over immunoprecipitated glycoproteins from (A) human CD34⁺ cells, (B) mouse LSK cells, or (C) KG1a cells at 0.6 dyne/cm². After cell perfusion, the numbers of rolling cells/mm² in 4 distinct fields of view were counted. To control for specificity of CHO-E binding to membrane glycoproteins, EDTA was added to the buffer containing CHO-E cells before use in adhesion assays; no cells bound in the presence of EDTA (data not shown). Nonspecific adhesion was assessed by perfusing mock-transfected CHO cells (CHO-M) over the same region of the blot (at CD44, CD43, and PSGL-1). Low levels of binding were observed using CHO-M cells, and these values were subtracted from the values measured using CHO-E cells. Results shown reflect multiple assays (n = 4) on HECA-452 blots of multiple (n = 3) membrane preparations. Data are mean ± SEM.