19 to 24 kb of intronic sequence between exons 3 and 4 was replaced with 6 to 7 copies of the pL116 transgene, which contained the entire bovine papilloma virus (BPV) genome, the human growth hormone-releasing factor gene (hGRF) driven by the mouse metallothionein I promoter and plasmid pMl2d sequences. (J:82720, J:181260)