Figure 3. Effects of BEZ235 on survival under hypoxia. (A) SQ20B cells were exposed to 0.5% O₂ for 24 h, and then treated with BEZ235 for 24 h. The cell viability was measured by the MTT assay. (B) SQ20B cells were exposed to 0.5% O₂ for 24 h, and then treated with BEZ235 for 24 h. After 10 days the colonies were stained and counted. The graph underneath shows the surviving fraction ratios under hypoxia and normoxia (plating efficiency in the presence of BEZ235 divided by plating efficiency in the controls without the drug). (C) SQ20B cells were exposed to 0.5% O₂ for 24 h, then treated with BEZ235 for 1, 3, 6, 16 and 24 h prior to protein harvesting. Proteins were analyzed by SDS-PAGE and immunoblotting with antibodies as shown. (D) SQ20B cells were exposed to 0.5% O₂ for 24 h, and then treated with BEZ235 for 24 h. Cell death detection ELISA was used to quantitate the cytoplasmic oligonucleosomes as a measure of apoptosis.