ATP4B and neuroendocrine neoplasm: This finding was substantiated using gene set enrichment analyses (GSEA) by comparing the d90 tumor versus normal tissue ranked gene list with a list of 399 genes preferentially expressed after transdifferentiation of ATP4B-expressing gastric preparietal progenitor cells (pPC), without neuroendocrine features, into locally invasive or metastatic neuroendocrine tumor cells (iGC/mGC) in gastric tumors of Atp4b promoter-SV40 TAg-transgenic mice (Table 5 in [4]).