Puromycin dihydrochloride, also known as Stylomycin hydrochloride, is an aminonuclease antibiotic used for selection and maintenance of cell lines expressing a transfected pac gene, whose product, puromycin-N-acetyl-transferase, inactivates puromycin via acetylation. Puromycin dihydrochloride has been cell culture tested and is recommended for selection of stably transfected cells following transfection with Santa Cruz Biotechnology shRNA or Lentiviral particles. Puromycin dihydrochloride is an antibiotic substance produced by the soil actinomycete Streptomyces alboniger which induces apoptosis in cells by interfering with RNA function, leading to inhibition of protein synthesis. Puromycin dihydrochloride is thought to act as an acyl-tRNA analogue causing premature chain termination. Toxic to both eukaryotic and prokaryotic cells, Puromycin dihydrochloride has also been shown to arrest cells in G2/M phase.