CD24 has been identified as a ligand to P-selectin (Sammar et al, 1994), and it is conceivable that this function contributes to a more aggressive metastatic behaviour of CD24-positive tumour cells, as in vitro evidence suggests (Aigner et al, 1995,1997,1998; Friederichs et al, 2000). The gene discussed is SELP; the disease is neoplasm.