SFRP5 and breast cancer: In particular, we found that SFRP2 and SFRP5 are methylated at even higher frequencies than SFRP1. Taken together, our findings indicate that the majority of breast tumours harbour methylation of at least one Wnt antagonist gene, and support the hypothesis that epigenetic silencing of Wnt antagonist genes is a major cause of constitutive Wnt signalling in breast cancer.