The expression of mGluR1 (GRM1) and mGluR5 (GRM5) was conserved from primary tumours to metastatic samples, but moderate changes were evident for other receptors such as mGluR2/3/7/8 (GRM2, GRM3, GRM7, and GRM8) (Figure 2A). This evidence concerns the gene GRM5 and neoplasm.