PDCD1LG2 and lung carcinoma: Our ChIP‐seq and cDNA microarray analyses indicated that ectopic NKX2‐1 bound to the locus of PD‐L1/PD‐L2 (Fig 4A and Appendix Fig S1) and induced the expression of PD‐L1 and PD‐L2 in mucus‐producing A549 human lung carcinoma cells (Fig 4B; Maeda et al, 2012), which was also confirmed at the protein level in A549 cells and other mucus‐producing lung cancer cell lines (Fig 4C and D).