GRM4 and glioma: Recent studies had indicated that mGluR4 participates in the process of cell proliferation, differentiation, and survival in several different cell types which include neural stem cells (NSCs), granule neuroprecursors, bladder cancer, glioma, etc. For example, our previous study showed that mGluR4 activation regulated proliferation, neuronal differentiation, and survival in rat NSCs (Zhang et al., 2015, 2020).