NCAM1 and gastrointestinal stromal tumor: In clinical practice, imatinib combined with IL-2 stimulates circulating NK cells in GIST patients [135, 198] and increases the expression levels of HLA-DR, TNF-related apoptosis-inducing ligand (TRAIL) and CD56 in NK cells; the abundance of HLA-DR+ NK cells is reported to be associated with PFS and OS in GIST [135, 198].