At cellular level, we found that stable knockdown of PD-L2 in human NSCLC cell lines (H1975 and H460) by small hairpin RNA (shRNA) (Supplementary Fig. 7) reduced CCL20 mRNA expression revealed by qRT-PCR assay (Fig. 3c). The gene discussed is PDCD1LG2; the disease is non-small cell lung carcinoma.