Alternative splicing can generate different isoforms that are expressed at similar levels after T cell activation (Shinohara et al., 1994; Keir et al., 2008); however, genetic variants at PDCD1 coding and regulatory 5’ and 3’ untranslated regions (UTR) may influence protein levels and the natural history of cancer development (Tao et al., 2017; Wang et al., 2018). Here, PDCD1 is linked to cancer.