Fig 1: Increased susceptibility to Illudin S and inefficient RRS in PARP1-impaired cells. (A, B) PARP1 depletion or inhibition reduces the clonogenic survival of cells after Illudin S. (A) Clonogenic survival of GMU6 cells to Illudin S (1 ng/ml) for 24 h without or with 2 µM PARPi ABT-888 or PARP1-kd (GMshPARP1). Bars represent mean ± standard deviation (SD; n = 3). Note: In all panels of this and subsequent figures, * denotes statistically significant difference with unpaired two-tails t-test (P-value <.05). (B) Clonogenicity of U2OS cells with indicated genotypes to dose-response of Illudin S (n = 4). (C–E) PARP1-impaired cells exhibit reduced RRS after DNA damage. (C) Images of GMU6 cells without or with PARPi, GMshPARP1, and CS-B cells 1 h after EU labelling at specified time of Illudin S treatment. The data of three biological replicates is expressed as mean ± standard error (SE) of relative fluorescence intensity (RFI, arbitrary units). Note that the error bars are smaller than the time point markers. (D, E) As in panel (C), but after UVC irradiation (10 J/m2) in GMU6 (D) and U2OS (E) cells with indicated genotypes.