Detection of radiosensitization by automated cell counting in a high-throughput siRNA library screening setting. (a) Box-and-whisker plots depicting the data of the positive and negative siRNA controls included in the screen. The whiskers indicate the 2.5th/97.5th percentiles. Outliers are depicted by individual dots. (b) Robust Z’ factors of the four screening sessions. Each circle represents the result of one session, with IR (closed circles) or without IR (open circles). (c) Volcano plot of the combined effect of gene silencing and IR on cell survival. The plot depicts the interaction t-statistic and percent false discovery rate (FDR) of all siRNAs in a genome-wide siRNA screen targeting approximately 21,000 human genes. Radiosensitizing siRNAs exhibit a negative t-statistic and low FDR. The position of siMAD2L2 (t-statistic = − 0.61; FDR = 8.9%) is indicated.