For this, we used quantitative methylation-specific PCR (Q-MSP) to evaluate promoter methylation of a panel of cancer-associated genes in a large cohort of clinically well-characterized NSCLC samples, including calcitonin-related polypeptide alpha (CALCA), E-cadherin (CDH1), death-associated protein kinase 1 (DAPK1), iroquois homeobox 1 (IRX2), TIMP metallopeptidase inhibitor 3 (TIMP3), and paired box 6 (PAX6). Here, IRX2 is linked to cancer.