For example, the promoter DNA methylation levels of MUC1 increased significantly in non-ADC (NEC and HAS) compared to ADC, or in ADC with poorer differentiation states compared to ADC with better differentiation states, for the 4/6 mGC patients, and the promoter chromatin accessibility levels of MUC1 also showed a decreased tendency in the four patients (although not statistically significant in two patients), indicating that the decreased expression levels of MUC1 were likely to be regulated by both decreased chromatin accessibility and increased DNA methylation levels (Fig. S9B). This evidence concerns the gene MUC1 and neuroendocrine carcinoma.