SIRT6 and neoplasm: Several studies showed that NB metastatic cells express distinctive features from primary tumor cells, including down-regulation of several tumor suppressor genes (i.e., SIRT6, BBC3/PUMA, STK11, CADM4 and GLTSCR2) and up-regulation of immunosuppressive molecules, such as calprotectin and HLA-G [29,30].