Previous work has shown that CD8+ T cells are responsible for rejection of E.G7-OVA tumours and that administration of an anti-CD4 monoclonal antibody, that mediates regression of established E.G7-OVA tumours, leads to increased infiltration of CD8+ cells (Vasovic et al, 1997; Dyall et al, 1999). The gene discussed is CD4; the disease is neoplasm.