In vitro, the treatment of different colorectal cancer cell lines (SNU-61, SNU-81, SNU-407, SNU-1033, SNU-1047, SNU-C2A, SNU-C4, and SNU-C5) with the mGluR4 agonist (L-AP 4) increased the proliferation only in SNU-81 cells. Here, GRM4 is linked to colorectal cancer.