ECs are defective in HR repair.

<p>A) EC cells are defective in RAD51 foci assembly. The indicated cell lines were treated with a pulse of cisplatin (3.3 µM for 6 hs) and co-stained with anti-RAD51 (red) and anti-bromodeoxyuridine (BrdU, [green]) antibodies. Harrows points to representative BrdU-positive (S-phase) cells used for RAD51 quantification (see below). B) cisplatin induces a comparable damage in U2OS and EC cell lines. The indicated cell lines were treated as in A, co-stained with γH2AX (red) and BrdU (green) antibodies, and counterstained with DAPI (blue). Harrows points to representative BrdU-positive (S-phase) cells used for γH2AX quantification. C–D) quantification of the number of RAD51 (C) and γH2AX (D) foci, before and after cisplatin treatment. Data are mean value ±s.d. of two independent experiments. In C and D a minimum of 100 nuclei were counted for each cell line. Statistical analysis was performed using a paired two-tailed Student's <i>t</i>-test (P<0.05). E) 27x-1 and Tera-1 cell lines are defective in I-SceI-induced DSB,repair, by HR. Percentage of GFP+ cells measured by flow cytometry, 48 hs upon the transfection with both DR-GFP and I-SceI expression vectors (black bars, [DR-GFP+I-SceI]). Data were normalized against the transfection efficiency measured by transfecting a (constitutive) GFP-expressing vector (white bars [NZE CAG]). Data are mean value ± s.d. of three independent experiments. Statistical analysis was performed using a paired two-tail Student’s t-test (P<0.05). For more details see also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0051563#pone.0051563.s003" target="_blank">Fig. S3A</a>–B.