Using the HPRT mutation assay, we showed that SNAP-treatment leads to a ∼2-fold increase in the mutant frequency in Msh2−/− pre-B cells (Figure 1D) and in the MMR-deficient human colon cancer cell line DLD-1 (Figure 1E), but not in their respective controls. Here, MRC1 is linked to malignant colon neoplasm.