The nm23 gene family Is widely documented as a suppressor of the metas
tatic phenotype in many human cancers. However, its role with respect
to the invasive behavior of primary central nervous system tumours has
scarcely been addressed This review describes the members of this fam
ily identified to date and outlines the in vitro and in vivo data gath
ered from nearly ten years of nm23 research within the context of mali
gnant progression in peripheral tumours. It is clear that this is an a
rea which can no longer be ignored by the brain tumor community. Human
nm23 bears strong sequence homology to the awd gene in Drosophila, mu
tations in which cause abnormal morphology of larval neural tissue. Th
e functions and possible mechanisms underlying the ability of nm23 to
suppress metastatic behavior are discussed.