BI-1 overexpression inhibited PYZD-4409–induced cell death. HT1080–BI-1 and HT1080-neo cells (3 × 10³) were seeded overnight in 96-well plates. The next day, cells were treated with increasing concentrations of PYZD-4409 for 24 hours. Cell growth and viability was determined by the Alamar Blue assay. Data represent the mean percentage ± SD of viable cells relative to control (n = 3). A representative experiment is shown.