While we did not find an effect of ARID1B knockdown on 53BP1 foci formation, a marker of NHEJ, in any of the CRC cell line, this does not rule out a role of NEHJ on the observed radiosensitizing effect of ARID1B knock down in ARID1A mutated CRC cell lines. The gene discussed is ARID1B; the disease is colorectal carcinoma.