Schematic diagrams of five plasmids used in demonstrating function of the φC31 integrase. (A) pInt, a plasmid for expression of φC31 integrase in E. coli. (B) pCMVInt, for expression of integrase in mammalian cells. (C) pBCPB+, intramolecular integration assay vector. (D) p220KattBfull, an EBV vector bearing attB, the target for integration events. (E) pTSAD, the donor for integration events, bears attP. KanR, AmpR, ChlorR, HygR, genes for resistance to kanamycin, ampicillin, chloramphenicol, and hygromycin, respectively; SV40, simian virus 40; EBNA-1, Epstein–Barr virus-encoded nuclear antigen 1.