Although we regard the inhibition of tumor cell motility by ICAM-2 in vitro to be compelling evidence that ICAM-2 participates in cell functions distinct from immune responses, we acknowledge the complex nature of metastatic tumor progression and propose that our data suggest multiple hypotheses with respect to the mechanism by which ICAM-2-inhibits neuroblastoma cell motility. This evidence concerns the gene ICAM2 and neoplasm.