MLH1 and colorectal carcinoma: To determine whether reconstitution of MLH1 and MSH3 in the MSI-H CRC line HCT 116 would revert WRN dependence, we utilized variants of HCT 116 harboring copies of human chromosome 2 (+ch2, control line), chromosome 3 (+ch3, MLH1 reconstitution) or chromosome 3 and 5 (+ch3+ch5, MLH1 and MSH3 reconstitution) derived from normal fibroblasts (Haugen et al., 2008; Koi et al., 1994).