JUN and neoplasm: Such studies can reveal the tumor-specific epigenetic characteristics related to metastasis and the heterogeneity of tumor populations.344,345 Gkountela et al. analyzed the DNA methylation patterns of CTCs from BRCA patients and tumor xenograft models in NSG mice and discovered numerous differentially methylated regions (DMRs) in CTCs.5,346 CTCs showed lower DNA methylation levels of genes such as JUN, MIXL1, SHOX2, and MEF2C, which are often enriched in various types of cancer.