Agilent offers a comprehensive collection of competent cells for difficult protein expression, including specialty strains for a large variety of applications. These competent cells provide the highest levels of recombinant protein expression in E. coli. The BL21-CodonPlus cells dramatically improve protein expression in E. coli by overcoming the problem of codon bias. ArcticExpress Competent Cells are engineered to address the common bacterial gene expression hurdle of protein insolubility. With our cold-adapted ArticExpress RIL and ArcticExpress RP Competent Cell lines, you can enhance protein solubility and correct for codon bias at the same time. BL21 and BL21-Gold strains provide the tightest control of protein expression for extremely toxic proteins.