Bufalin increases the sensitivity of GSCs to TMZ. (A) GSCs derived from U87MG and LN-229 cells were treated with bufalin (0, 10, or 20 nM), TMZ (25 μM), or combination of bufalin and TMZ for 48 h, and the cell viability was assessed by MTT assay. **p < 0.01, ***p < 0.001. (B) GSCs derived from U87MG and LN-229 cells were treated with bufalin (0, 10, or 20 nM), TMZ (25 or 50 μM), and a combination of bufalin and TMZ for 72 h. Cell apoptosis was detected by flow cytometry, and the proportion of apoptotic cells is presented as the mean ± SD. *p < 0.05, **p < 0.01, ***p < 0.001. (C) Western blot analysis for p-Bad, Bcl-2, Bcl-xL, caspase 9, and GAPDH. All experiments were repeated three times. TMZ, temozolomide; Bcl-2, B-cell lymphoma-2.