PDCD1 and cancer: We previously demonstrated in an ex vivo A549 cancer cell-T cell interaction assay that peripheral blood T cells from NSCLC cancer patients need to be TCR stimulated to co-upregulate PD-1 and LAG-3 (Zuazo et al, 2019), and to induce the transcriptional transactivation of E3 ubiquitin ligases (Karwacz et al, 2011).