Using array-based analyses, significant differences in the CpG-methylation patterns between tumor tissues and matched controls were observed for CTLA4 and PDCD1 (PD1) (FDR < 0.01; Fig. 1a, b): NSCLC tumors exhibited a decreased degree of CpG-methylation in these loci compared to tumor-free tissues. The gene discussed is PDCD1; the disease is non-small cell lung carcinoma.