Fig. 3

NID2 methylation level on the specific site is higher in the cancer tissues compared with that in the normal oral epithelium. a The bisulfite-converted DNA of the normal oral epithelium and cancer samples were amplified using the quantitative PCR at methylated NID2 with a specific probe. b Universal standard methylation controls were amplified using the real-time PCR (left) and then calculated into standard curve (right). c These bisulfite-converted DNA samples from the healthy controls, smokers, and patients with OSCC were amplified with a specific probe, and the methylation level was estimated referring to the standard curve. d Comparison of the effective collection approaches between oral rinse and oral swab in detecting NID2 methylation