SLC38A1 and central nervous system cancer: A plausible explanation for this phenomenon is that SLC1A5 is lowly expressed in partially CD133+ glioma cells isolated from GBM tissues.[42] Another explanation for this phenomenon is that glutamine transporter mainly includes SLC38A1, SLC1A5, and SLC6A14.[43] SLC1A5 knockdown reduced the level of glutathione.