G 418 disulfate salt is widely used as a selective agent in molecular and cell biology for the selection of eukaryotic cells transfected with resistance genes. It is commonly employed in gene expression studies where cells are engineered to carry the neo gene, which confers resistance to G 418. This allows researchers to eliminate non-transfected cells and maintain stable cell lines expressing desired genetic constructs. It is effective in both mammalian and yeast cell cultures, making it valuable in generating transgenic cell models, studying gene function, and producing recombinant proteins. Due to its ability to inhibit protein synthesis by interfering with ribosomal function, only cells expressing the resistance gene survive in its presence, enabling efficient selection. G 418 is also used in developmental biology and stem cell research to maintain selection pressure during long-term cultures. Its reliability and broad spectrum of activity across cell types make it a standard tool in genetic engineering workflows.