Regional mapping of the Lyp gene by FISH to normal human lymphocyte chromosomes counterstained with DAPI. Biotinylated cDNA probe was detected with avidin-FITC. Separate images of DAPI counterstained metaphase chromosomes and of LyP cDNA probe hybridization signals were captured and overlaid electronically as described in Materials and Methods. Part of a representative metaphase preparation is shown to indicate the position of the Lyp probe FISH signals that are visible as two yellow fluorescent spots on the p arm of chromosome 1. A DAPI banded chromosome 1 together with schematic ideogram is shown to indicate that the Lyp1 probe hybridizes to band 1p13.