SLC17A7 and neoplasm: GC-specific deletion of meningioma expressed antigen 6 (Mea6), initially found in tumor cells (Heckel et al., 1997), resulted in a reduction of PF-PC synapse formation, presumably due to impaired intracellular transportation of molecules required for synapse formation, including vesicular glutamate transporter 1 (vGluT1) and brain-derived neurotrophic factor (BDNF; Wang et al., 2021).