Anti nbs1

Cells grown on coverslips were prepared for IF by standard procedures. The following antibodies were used for immunostaining: anti-ATRX (Santa Cruz sc-15408); anti-ATRX 39f [38] (link); anti MRE11 (Abcam ab214); anti-MRE11 (Calbiochem PC388); anti-RAD50 (Abcam ab89); anti-PCNA (Santa Cruz sc-9857); anti-RPA32 (S33) (Bethyl A300-246A); anti-NBS1 (BD Biosciences 611871); anti-53BP1 (Novus Biologicals NB100-305); For MRN co-localisation studies cells were pre-permeabilised prior to fixation with ice cold 0.5% Triton X-100. For MRE11/ATRX/PCNA co-localisation in mES cells, cells were attached to coverslips via poly-l-lysine treatment prior to pre-permeabilisation. Telomere FISH was performed subsequent to antibody incubation using Telomere PNA FISH Kit/Cy3 (Dako K5326).

The following commercial antibodies were used: anti-DNA-PK_cs phospho-S2056 (Abcam, ab124918), anti-MRE11 (Abcam, ab214), anti-RAD50 (BD Bioscience, 611010), anti-NBS1 (BD Bioscience, 611871), anti-ATM (Abcam, ab109027), anti-ATM phospho-S1981 (Abcam, ab81292), anti-MDC1 (Abcam, ab5003), anti-KAP1 (Bethyl Laboratories, A300–274A), anti-KAP1 phospho-S824 (Bethyl Laboratories, A300–767A), anti-phospho-H2AX (S139) (EMD Millipore, 05–636), anti-γH2AX (Cell Signaling Technology, 7631), anti-tubulin (Sigma, T5168), anti-CHK2 phospho-T68 (Cell Signaling Technology, 2197), anti-CHK2 antibody (Cell Signaling Technology, 2662), anti-XLF (Cell Signaling Technology, 2854), anti-LIG4 antibody (Cell Signaling Technology, 14649), anti-Histone H3 antibody (Cell Signaling Technology, 9715), anti-XRCC4 antibody (Santa Cruz, sc-271087), and anti-EXO1 (Thermo Fisher Scientific, MA5–12262). In-house produced antibodies include mouse monoclonal antibodies against DNA-PK_cs (25–4), Ku80, and Ku70. Secondary antibodies included anti-mouse IgG (HRP-linked) and anti-rabbit IgG (HRP-linked), which were purchased from Cell Signaling Technology.