Quantification of apoptotic proteins in newly diagnosed childhood acute leukemia. A representative blot for cells of 9 acute leukemia samples incubated with monoclonal anti-PARP antibody is depicted in the top panel. The dilution series consists of 30, 25, 20, 15, and 10 μg Reh protein lysate. The presence of PARP was detected by enhanced chemiluminescent staining and the signal intensity was quantified by densitometry and plotted (bottom). This graph was used to estimate the relative quantity present in the patient's sample compared with the Reh cell line dilution series by linear regression. The 9 samples shown here are part of the group of 53 patients and include 3 B-lineage ALL samples, 3 T-lineage ALL samples, and 3 AML samples. OD indicates optical density.