SFRP1 and colorectal carcinoma: Figure 7 shows the correlation between the DNA expression of SFRP1/2 and the methylation levels of SFRP1/2, the prediction of the CpG islands in SFRP1/2, and the expression of the methyltransferases DNMT1, DNMT3A, and DNMT3B, all obtained from the CRC analysis in the TCGA database.