CD70 protein, whether expressed on dendritic cells (Hintzen et al, 1995), B cells (Rowley and Al-Shamkhani, 2004), tumour cells (Arens et al, 2001), or introduced as soluble protein (Kelly et al, 2002), promotes the survival and expansion of antigen-primed CD8+ T cells in the mouse, through dose-dependent stimulation of CD27 activity. Here, CD27 is linked to neoplasm.