PRF1 and squamous cell lung carcinoma: Lactate dehydrogenase (LDH) release assays revealed that the cytotoxic activity of pNK cells against the NSCLC target cell line A549 was suppressed compared to that of pNK cells from healthy volunteers (Fig. 1a), and the expression of the NK cell function-related gene PRF1 (perforin) was significantly reduced in lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC) (Supplementary Fig. 1c).