Fig. 4.
FEN1 down-regulation underlies synthetic lethality in RAD54B-deficient human cells. (A) Graphical representation of the percentages of cells relative to GAPD knockdown (± SEM) are shown for the isogenic RAD54B+/+/+ and RAD54B−/−/− cells treated with the various siRNAs indicated (x-axis). A single representative data series collected in sextuplet and compiled from 1 of 3 experiments is shown (see Table S3). Highly statistically significant differences (P <0.0001) in the mean percentage of cells relative to GAPD knockdown as determined by Student's t- test (see Table S4) are identified (***). (B) Live cell imaging coupled with PI incorporation into dead/dying cells reveals an increase in death in RAD54B deficient (black) cells treated with FEN1 siRNAs versus RAD54B-proficient (gray) cells treated similarly. Five non-overlapping images from each well were collected every 2 h for 48 h and the total number of PI-positive nuclei were scored. All data were normalized to the first time-point (t = 0) to permit easy comparisons between the respective siRNA treatments indicated at the top. Each graph depicts a single representative experiment performed in triplicate and repeated at least once. Note that the relative death index (y-axis) scale is different for the PLK1 positive control.