Puromycin dihydrochloride is widely used as a selection agent in cell culture systems. It effectively kills eukaryotic cells that do not carry resistance genes, making it ideal for selecting genetically modified cells. It is commonly used in stable transfection experiments where cells are engineered to express puromycin N-acetyl-transferase, an enzyme that confers resistance. It is also used in protein synthesis studies because it acts as an analog of the aminoacyl-tRNA molecule, causing premature chain termination during translation. This property makes it valuable in research involving gene expression and ribosome function. In addition, puromycin is used in the generation of knockout and knockin cell lines via CRISPR/Cas9 or viral transduction, where rapid selection of transfected or transduced cells is required. Its fast action typically results in cell death within 1–3 days, allowing for quick validation of transfection efficiency and selection of pure cell populations.