Cytotoxic activity of cisplatin and TW-37, a small molecule inhibitor of Bcl-2, in endothelial cells and head and neck cancer cells. A–D, The cytotoxicity of cisplatin and TW-37 on human dermal microvascular endothelial cells (HDMEC), oral squamous cell carcinoma-3 (OSCC3), and two University of Michigan squamous cell carcinoma cell lines (UM-SCC-1 and UM-SCC-74A) was determined by SRB assay. Cells were exposed to 0–50 µM cisplatin or TW-37 for 72 hours. Results are normalized against vehicle control and initial plating density. Experiments were performed in triplicate wells per condition, and graph is representative of three independent experiments.