DMSO plate values from a 1536-well plate. Columns 1, 2, and 5 to 48 received DMSO (0.5% final concentration). Column 3 received a titration of camptothecin (50 µM down by 1:2 dilutions), and column 4 received 50 µM camptothecin. The cells were plated at 1000 per well and were treated for 18 h. The signal-to-background ratio (SB, n = 3, with 32 wells for 50 µM camptothecin and n = 1408 wells for DMSO, per trial), Z′ score (Z′, n = 3 with 32 wells for positive and 1408 wells for negative), and V score (V, n = 3 per 12 concentration dilution series) are listed in the figure.