The tumour size, 160±28 mm3 for placebo tumours and 228±60 mm3 E2-treated tumours, was in the range previously described by our lab using B7-1/IL-2 and other cytokines delivered to PyMT tumours by adenoviral vectors (Addison et al, 1998; Emtage et al, 1998; Palmer et al, 2001). This evidence concerns the gene CD80 and neoplasm.