In addition, NK cell activation of DCs in anti-tumour immunity appears to depend upon tumour expression of NKG2D ligands (Adam et al, 2005), or expression of costimulatory molecules such as CD70, CD80 or CD86 (Kelly et al, 2002); EMT6 tumours are immunogenic (Siemann et al, 1981) respond well to PDT (Korbelik and Dougherty, 1999) and may be more susceptible to immune-mediated control. This evidence concerns the gene CD70 and neoplasm.