Expression of recombinant TAT-Apoptin protein in three different E. coli strains. The TAT-Apoptin protein expression in three E. coli strains, BL21(DE3), BL21(DE3)pLysS and BL21(DE3)CodonPlus-RP, which were transformed with either pET-TAT-VP3 or pGEX-TAT-VP3 and cultivated at 37 °C. His-TAT-Apoptin and GST-TAT-Apoptin protein were examined and detected using SDS-PAGE (A, C) and Western-blotting (B, D). Anti-His and anti-GST tag monoclonal antibodies was respectively used to recognize the His-TAT-Apoptin protein and GST-TAT-Apoptin. Lane M, pre-stained protein marker; the symbols “-” and “+” represented pre-induction and post-induction with 1 mM of IPTG over 4 hrs of cultivation in E. coli, respectively.