We found that PD-L2 was increased (PD-L2tumor/PD-L2normal > 1) in 68.9% (31/45) of lung cancer specimens compared to their counterpart normal lung tissues (Supplementary Fig. 14, Table 1), while the percentage of PD-L2 overexpression in smoker patients reached 14/17 (82.4%), much higher than that in non-smoker patients (6/15, 40%; Table 1). This evidence concerns the gene PDCD1LG2 and lung carcinoma.