p16/p15 deletions in matched diagnostic and relapse ALL specimen pairs. Autoradiogram of a blot containingBamH1-digested DNAs cohybridized with p16 and MLLcDNA probes. The locations of the germline p16,p15, and MLL bands are indicated by arrows at right. The migration of molecular size markers are shown in kilobases on the left. Samples include DNA from dilutions of the K562 cell line, which has homozygous p16 and p15 deletions, into normal DNA to simulate deletions in 50% and 10% of the cell population; a healthy control (NORM); K562; and four matched diagnostic (Dx) and relapse (R) patient samples (no. 4, 10, 17, 6). The gene status ofp16 and p15 is listed above each patient sample (G, germline; D, deleted). Faint residual p16 and p15 bands (<10%) in no. 6 relapse patient sample are due to contamination with small amounts of normal cells.