G418 also known as G-418, G418 sulfate or Geneticin is a high-quality selective antibiotic for eukaryotic cells, provided as a sterile, cell culture-tested solution. This aminoglycoside antibiotic, similar in structure to gentamicin B1, is produced byMicromonospora rhodorangea. G418 blocks polypeptide synthesis by inhibiting the 80s ribosomal subunit, thus disrupting proofreading and the elongation step, in both prokaryotic and eukaryotic cells.