TMEM196 and in situ carcinoma: The frequency of TMEM196 methylation correlated with the pathological severity of lung carcinogenesis, with a gradual increase in methylation frequency from 14.8% (4/27) in squamous metaplasia, 29.7% (11/37) in dysplasia, 40.0% (12/30) in carcinoma in situ (CIS), and finally 52.0% (13/25) in infiltrating carcinoma samples (Supplementary Table S2).