Cytogenetic mapping of a multisite BAC. Distribution of hybridization signals on C57BL/6J metaphase spreads from clones RP23-110E20 (red) and RP23-106H14 (green), marker for Chromosome 9. RP23-110E20 was selected from the RP23 library by an STS that mapped to 21.6 Mb on Chromosome 9. We observed hybridization signals at two sites on Chromosome 9 in addition to regions on Chromosomes 5, 7, 12 (2 loci), 14, and 17. Note that at least four out of a total of eight hybridization loci showing hybridization with RP23-110E20 are located in the proximal 1/3 of the corresponding chromosomes. The arrows indicate the positions of the RP23-110E20 hybridization signals.