PNPO and type 2 diabetes mellitus: Compared to non-expressing cells, the PNPO+ cells were characterized by the enrichment for genes involved in “insulin secretion,” “carbohydrate digestion and absorption,” “AMPK signaling,” “maturity onset diabetes of the young,” “type I diabetes mellitus,” “type II diabetes mellitus,” “Parkinson disease”, etc., according to the Kyoto Encyclopedia of Genes and Genomes (KEGG) (fig.