GRM5 and cancer: Only a few reports demonstrated that the tumor size, presence of lymph node metastases and cancer stage were significantly related to high NR1 (Choi et al. 2004) and mGluR5 (Park et al. 2007) expression in oral SCC, whereas significantly lower expression levels of mGlu4 receptors were correlated with spinal cord metastases, CSF spreading, and recurrence of medulloblastoma (Iacovelli et al. 2006).