Sensitivity of I-45 and I-45-BTZ-R cells to cisplatin. I-45 and I-45-BTZ-R cells were treated with cisplatin (0.63 μM to 40 μM) for 72 hours. Cell viability was determined following treatment using the XTT assay. Control cells were treated with PBS and their viability was set as 100%. Values are the mean ± SD of triplicate assays from two experiments.