Distribution patterns of promoter methylation of the 6 genes in NSCLC. Q-MSP was performed as described in Materials and Methods. The relative methylation level (on Y axis) is represented by ratios of candidate gene/β-actin × 1000, except for PAX6/β-actin × 100. Horizonal lines indicate a 95% normal confidence interval for the sample mean. T, tumor tissues; N, nonmalignant lung tissues. **, P < 0.01; ***, P < 0.001.