A number of tumours and tumour cell lines have also been reported to develop a permanent and selective IFN-γ insensitivity, such as testicular germ cell tumours, RCC cell line, basal cell carcinoma of the skin and human lung adenocarcinoma cell lines (Kooy et al, 1998; Dovhey et al, 2000; Nagao et al, 2000; Schweyer et al, 2002, 2003; Dunn et al, 2005b). This evidence concerns the gene IFNG and childhood testicular germ cell tumor.