For example, mucin 1 (MUC1), which is a member of the mucin family, significantly down-regulated in ADC with poorer differentiation states than in ADC with better differentiation states, and significantly down-regulated in non-ADC (NEC and HAS) compared with ADC within the same mGC patient (Fig. 4A), which was also validated by IHC staining at protein levels (Fig. 4B). The gene discussed is MUC5AC; the disease is neuroendocrine carcinoma.