... responsible for the proper identity of abdom-inal segments 5–8, while three other transcripts arerequired for the identity of abdominal segment 9 and also that of abdominal segment 10 (for examples ... A5, for example, only one of thefour Abd-B cis-regulatory regions, iab-5, is thought tobe active, while the other three are silenced. In A6, bothiab-5 and iab-6 are active, and iab-7 and iab-8 ... avoid other pro-moters, and to locate and physically approach theirproper target promoter in the viscous environment ofthe nucleus.Somatic pairing of chromosomes and the regulation of Abd-BA...