Mouse anti chk1

Cells were left to reach 70–80% confluence before cell lysates were harvested. Primary antibodies: rabbit anti-ATM (1:500, #2873, Cell Signalling), goat anti-ATR (1:500, # 1887, Santa Cruz), mouse anti-CHK1 (1:500, # 8408, Santa Cruz), mouse anti-Cyclin E (1:500, # 247, Santa Cruz), rabbit anti-DNA-PKcs (1:500, # 9051, Santa Cruz), mouse anti-Ku70 (1:500, #3114, Abcam), rabbit anti-Ku80 (1:500, #80592, Abcam), rabbit anti-PARP-1 (1:500, # 227244, Abcam), rabbit anti-RAD51 (1:500, # 8349, Santa Cruz), rabbit anti-XRCC1 (1:500, #11429, Santa Cruz), rabbit anti-ARID1A (1:1000, #12354, Cell Signalling). Ponceau-S staining was used to ensure equal loading of the protein.

Chromatin fractionation experiments were performed as previously described (23 (link)). Western blotting was performed using standard methods. Blots were incubated with primary antibodies against: rabbit anti-pCHK1(S345) (Cell Signalling Technology), mouse anti-CHK1 (Santa Cruz Biotechnology), rabbit anti-RAD51 (Bioss Antibodies), mouse anti-RPA32 (Calbiochem), rabbit anti-RPA70 (GeneTex), mouse anti-GAPDH (Millipore) and rabbit anti-Lamin B1 (Abcam). After incubations with horseradish peroxidase-linked secondary antibodies (1:20 000, Jackson Immunosciences), the blots were developed using the chemiluminescence detection kit WesternBright ECL HRP substrate (Advansta) according to the manufacturer's instructions. Quantification was performed on scanned images of blots using the Image Lab software, and the values shown on the graphs represent normalization of the protein content evaluated through LaminB1 or GAPDH immunoblotting.