As an example, the PRC2+-CGI promoter of DKK1 is hypermethylated and silenced in LumBRCA, PRAD and KIRC, but remains unmethylated and is upregulated in BasalBRCA, LUAD/LUSC, HNSC and EAC (Fig. 3f), which is consistent with earlier reports of ER-/PR-negative28 vs. luminal29 breast cancer and lung cancer30. This evidence concerns the gene DKK1 and breast cancer.