SA selectively inhibits proliferation of SF-295 and KR158 brain tumor cells, but has little effect on A549 lung tumor cells or primary astrocytes. A, Viability of KR158, SF-295, and A549 cells in response to SA was evaluated by XTT assay and plotted as a percentage of viable cells compared to cells treated with vehicle only. B, Viabilty of A549 cells in response to SA or CPT as evaluated by XTT assay. C, Viability of KR158 and four primary astrocyte cultures established from wt, Nf1−/+, or NPcis mice in response to SA was measured by XTT assay. Points, mean percentage growth of three wells.