Built for Tough Protein Expression. Designed for IPTG-inducible T7 systems, this BL21(DE3) derivative improves tolerance to toxic proteins while the pLysS plasmid suppresses basal expression for greater stability. Validated in 400+ publications, IG® C41(DE3)pLysS cells deliver dependable results for challenging protein expression. Custom formats, custom package sizes and bulk pricing are available upon request.