The methylation of deoxycytosine to form 5-methylcytosine (5mC) is an important feature of cancer. Extensive DNA methylation and transcription analyses have provided large quantities of data, but it is challenging to identify critical genes related to cancer development from these data. Researchers in Japan have developed a new mathematical method to extract appropriate information from the data, and successfully identified the gene TRAF4 as a key candidate for conferring resistance to anti-cancer drugs in gastrointestinal cancer.