Potential combinations of Sleeping Beauty components. (A) Cytoplasmic injection of an expression plasmid encoding Sleeping Beauty transposase and a plasmid carrying a SB-transposon; (B) Cytoplasmic injection of Sleeping Beauty-mRNA and a SB-transposon; (C) Injection of recombinant Sleeping Beauty protein and a SB-transposon; (D) In all possibilities stable transposition into a chromosome occurs, however, it is likely that A-C differ in the kinetics and potential remobilization events. CMV-SB100x, cytomegalovirus immediate early promoter driving a SB100x-cDNA; CAGGS, cytomegalovirus enhancer, chicken beta actin hybrid promoter driving a Venus-cDNA; ITR, SB specific-inverted terminal repeat; blue triangles, heterospecific loxP sites for a potential recombinase-mediated cassette exchange [25].