G 418 disulfate salt solution is widely used as a selective agent in molecular biology for the selection of eukaryotic cells transfected with resistance genes. It is commonly applied in cell culture systems to maintain and select genetically engineered mammalian, yeast, or plant cells that carry the neo (neomycin phosphotransferase) resistance gene. The compound effectively inhibits protein synthesis by interfering with ribosomal function, leading to cell death in non-resistant cells. This makes it essential for establishing stable cell lines and verifying successful gene integration. Due to its ability to penetrate both bacterial and eukaryotic cells, it is also used in certain cases for selection in prokaryotic systems, though less commonly. Its stability in aqueous solution allows for convenient use in long-term selection processes.