Yes, we have several strains for protein expression. BL21(DE3) (NEB #C2527 ) is offered for routine T7 Expression and BL21 (NEB #C2530 ) for non-T7 Expression. NEB Express (NEB #C2523 ) is an enhanced BL21 derivative and NEB Express Iq (NEB #C3037 ) offers tightly controlled expression from vectors with lac, tac, trc, or T5-lac0 promoters. T7 Express Competent E.coli (NEB #C2566 ) and T7 Express Iq Competent E. coli (NEB #C3016) are enhanced derivatives of BL21(DE3). The lacIq strain allows for tighter control of expression. Both are available with the lysY feature for exceptional control of expression. (T7 Express lysY, NEB #C3010 and T7 Express lysY/Iq, NEB #C3013 ). NEB also offers SHuffle™ strains that are capable of correctly folding proteins with multiple disulfide bonds in the cytoplasm. SHuffle™ Express (NEB #C3028H ) can be used with non-T7 promoters or SHuffle™ Express T7 (NEB #C3029H ) for T7 promoter expression vectors. For toxic T7 promoter expression, SHuffle™ Express T7 lysY (NEB #C3030H ) is ideal. These 3 strains are also offered as K12 strains; SHuffle™ (NEB #C3025H ), SHuffle™ T7 (NEB #3026H ) and SHuffle™ T7 lysY (NEB #C3027H ). Lemo21(DE3) (NEB #C2528 ) is available for tunable expression of difficult targets such as membrane proteins, toxic proteins and proteins prone to insoluble expression. NiCo21(DE3) (NEB #C2529 ) is designed for routine expression and purification of His-tagged proteins.