ITGA4 and neoplasm: Since these data strongly indicate a role for E-selectin in the adhesion of lung tumour cells to the cerebral endothelium, the expression of counter adhesion ligands and receptors on the tumour cells was investigated i.e. the E-selectin ligands sialyl Lewis X (sLeX) and P-selectin glycoprotein ligand-1 (PSGL-1), ICAM-1 receptors, lymphocyte function-associated antigen 1 (LFA-1α/CD11a) and macrophage-1 (Mac-1α/CD11b) and VCAM-1 receptor, very late antigen-4 (VLA-4α/CD49d).