BrdU Flow cytometry assay of U87-MG and DBTRG-05 cells exposed to CPT and SA-β Gal staining in treated U87-MG cells. A. Time dependent changes in DNA content following treatment, from 2 to 72 hours, of U87-MG and DBTRG-05 cells with 1 μM and 0.2 μM CPT, respectively. DMSO: solvent control B. SA-β Gal staining of CPT-exposed U87-MG cells (CPT) versus control (NT). For this purpose, a 72 h treatment with 1 μM CPT was performed. Counts were made on three random fields of about 100 cells.