The observation that PD-L is also expressed on some solid tumours and that blocking PDCD1/PD-L interaction actually accelerates tumour eradication in mouse models in vivo has pointed to involvement of PDCD1/PD-L in the suppression of anti-tumour immune responses and opened new doors for therapeutic intervention in cancer (Iwai et al, 2002; Curiel et al, 2003). Here, PDCD1 is linked to cancer.