COL6A1 and neoplasm: Our results showed that the methylation levels of COL6A1/2/3 in tumor tissues were significantly lower than in normal tissues, as follows: COL6A1 in ESCA, BRCA, UCEC, and PRAD; COL6A2 in LIHC, HNSC, KIRP, and BLCA; COL6A3 in HNSC, BRCA, UCEC, COAD, and PRAD.