CASR and gastrin-producing neuroendocrine tumor: We hypothesised that CaSR expression may be altered in GEP‐NETs as a result of epigenetic changes and investigated this hypothesis by examining CaSR expression in insulinomas, gastrinomas, and non‐functioning PNETs (NF‐PNETs), as well as methylation and chromatin state of the CASR gene locus in PNET cell lines.