GRM2 and sarcoma: In some clinical research settings (e.g., unexpected tumor and antibody concurrence), the demonstration that the tumor expresses the cognate antigen is critical to pathogenically associate it with the PNS (i.e., Yo antibodies in a man with gastric adenocarcinoma).e4 Similar studies are needed when there is limited experience with the PNS or associated antibody (i.e., mGluR2 antibodies and rapidly progressive cerebellar syndrome with sarcoma).e5