(A) A representative film of Southern blot analysis onEcoRI-digested DNA from ALL patients showing homozygous deletion of p16 exon 1 on lanes 1, 2, 11, and 14; heterozygous deletion on lane 5; and rearrangement on lane 3. Normal control was shown on lane 6, K562 cell line on lane 7 (homozygous deletion), and HL60 on lane 8 (heterozygous deletion) for comparison. A retinoic acid receptor α (RARα) probe was used with p16 exon 1 probe simultaneously to clarify DNA quality and amount. (1B) Two representative films of Southern blot analysis using p16 exon 2 probe and EcoRI restriction enzyme showing homozygous deletion of p15 exon 2 on lanes 1, 6, 8, and 9 and that of p16 exon 2 on lanes 1, 6, 8, 9, 11, and 12. Normel control was shown on lane 2, K562 cell line on lane 3 (homozygous deletion of both genes), and HL60 on lane 4 (hererozygous deletion).