Stock drug solutions are prepared in 100% dimethylsulphoxide (DMSO) (unless otherwise suggested by the supplier) at 10 mg/ml, and heated or sonicated if necessary to dissolve the sample. After use the stocks are kept at –20°C. For the assays, the compound is further diluted to the appropriate concentration using complete medium. The DMSO concentration in the wells with the highest drug concentration does not exceed 1%.
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