IRX2 and cancer: We assessed the promoter methylation of the 6 genes in a large cohort of well-characterized NSCLC subjects using Q-MSP technique in the present study, including CALCA, CDH1, DAPK1, IRX2, TIMP3, and PAX6. CALCA is known to encode a peptide hormone that plays a role in maintenance of calcium levels in blood serum and T-and B-cell regulation in certain malignancies, which is frequently methylated in multiple types of cancer [16,17].