Capizzi Capizzi E E Ricci Ricci C C Giunchi Giunchi F F Validation of the immunohistochemical expression of programmed death ligand 1 (PD-L1) on cytological smears in advanced non small cell lung cancer Validation of the immunohistochemical expression of programmed death ligand 1 (PD-L1) on cytological smears in advanced non small cell lung cancer Cancer Treat Res Cancer Treat Res 2018 2018 126 126 9 9 14 14. The gene discussed is CD274; the disease is non-small cell lung carcinoma.