Screening of the Prestwick Chemical Library. (A) Schematic representation of the three-step screening with hits yields. (B) Luminescence intensity of frataxin-deficient (R2C1) and control (R2m) untreated cell lines during the primary screening (14 plates for each cell line). Mean (M), standard deviation (SD), coefficient of variation (CV). (C) Effect of the 1,120 compounds of the library on the luminescence intensity in the control cell line R2m (upper panel) and in the frataxin-deficient clone R2C1 (lower panel) during the primary screening. Results are expressed as percentage of luminescence intensity compared to the same non treated cell line.