To test the hypothesis that TGFBR2 and ACVR2 frameshift mutations are dependent on the human MMR background, we constructed EGFP plasmids in which a −1 bp frameshift mutation at coding microsatellites of TGFBR2 exon 3 and ACVR2 exon 10 was detected by EGFP expression in human colon cancer cells with MMR deficiency. Here, ACVR2A is linked to mismatch repair cancer syndrome 1.