ABT-737 is more effective against neuroblastoma cell lines in hypoxia than in normoxia. A. SRB assays of cell number against ABT-737 concentration in normoxia (21% O2, open squares) compared with hypoxia (1% 02, closed diamonds). P< 0.05 for the comparison between normoxia and hypoxia by 2 way ANOVA for all cell lines except LA1-5S. Treatment durations were 24 hours for LA155n, 48hours for SH-EP1, NGP and IMR32, and 72 hours for SH-SY5Y and LA15S. B. Comparison of SRB IC50 value for ABT-737 between normoxia and hypoxia in neuroblastoma cell lines. P<0.01 for all cell lines by Student t-test.