Strikingly, gene-modified mice that cannot form the PD-L1/CD80 cis-heterodimer ameliorate anti-tumor T cell responses as well as autoimmunity, suggesting that the PD-1/PD-L1 inhibitory pathway is enhanced in the absence of the PD-L1/CD80 cis-heterodimer [40]. This evidence concerns the gene PDCD1 and neoplasm.