ARID1A and cancer: Mutations in epigenetic modifier enzymes KMT2B, KMT2C, KMT2D, and ARID1A were more prevalent in MSI cancers, where the majority possessed KMT2B and KMT2D mutations and over one-third had KMT2C and ARID1A mutations (χ2 test p = 0.001, Figure 1D).