MRE11 and carcinoma: However, when we re-expressed constructs for MRE11 isoform 1 or 2 in a bladder a cancer cell line which had been knocked down for endogenous MRE11 and used assays to assess their intrinsic radiosensitivity, no difference was observed between cells expressing the full length coding sequence for MRE11 (MRE11 isoform 1) or cells expressing MRE11 lacking exon 16 (MRE11 isoform 2).