FISH analysis of β globin YAC transgenic lines. Metaphase spreads from fibroblasts derived from transgenic lines A85.62 (left) and A85.68 (right). Upper panels are photomicrographs of chromosomes stained with DAPI (original magnification 1,000×). Lower panels show fields identical to those in the upper panels, with FITC labeling. β globin YAC sequences have integrated in chromosome 12 in line A85.62 and chromosome 5 in line A85.68.