Primary CNS cells are more vulnerable to BCNU and cisplatin than are cancer cells. Cells were plated on coverslips in 24-well plates at a density of 1,000 cells per well and allowed to grow for 24–48 h. On the basis of drug concentrations achieved in human patients, cells were exposed to (a) cisplatin (1 μM; for 20 h) or (b) BCNU (25 μM; for 1 h). Cell survival and viability was determined after additional 24–48 h (see Materials and methods). The rat neural cell types studied included O-2A/OPCs, oligodendrocytes, NRP cells, GRP cells, NSCs, and astrocytes. The normal human neural cell types consisted of human GRP and neuroepithelial precursor cells (human NEP). The tumor cells studied were the human malignant glioma cells UT-4, UT-12, and 1789, the colon cancer cell lines HT-29 and SW480, a meningioma cell line (Men-1), breast cancer cells (MCF-7), uterine cancer cells (MES), and ovarian cancer cells (ES-2). Each experiment was carried out in quadruplicate and repeated multiple times in independent experiments. Data represents mean of survival ± SEM, normalized to control values.