Transposition activity of various engineered Tol2 and piggyBac transposases. A. A schematic representation of tagged piggyBac and Tol2 transposases. B. The activity comparison between the wild-type and various epitope-tagged Tol2 and piggyBac transposases. C. The enzymatic activity of Myc-piggyBac. The enzymatic activity of Myc-piggyBac was measured under a fixed amount of pB-cassette3short (donor at 100 ng) co-transfected with increasing amounts of pCMV-Myc-piggyBac helpers (expressing the Myc-tagged piggyBac transposase) into HEK 293 cells. The lower panel depicts a Western blot indicating the expression level of the piggyBac transposase (detected by Myc antibody) and α-actin (detected by α-actin antibody) in the corresponding transfected cells. Western blotting was performed by isolating protein extracts from the remaining transfected cells of the same triplicate samples for the colony formation assay shown above.