The tight junction-related gene CLDN11 was selected because the relative CLDN11 methylated DNA enrichment was high (4.87-fold) in NPC cells (Fig. 1 and Additional file 3: Figure S1) and the CLDN11 mRNA expression reduction fold-change in NPC tissues was also high (46.34-fold, Normal/Tumor; Fig. 1), suggesting that CLDN11 is hypermethylated and downregulated in NPC. Here, CLDN11 is linked to neoplasm.