DKK1 and breast cancer: We examined the correlation of the expression of SOX2 and Wnt pathway effector genes AXIN2 and DKK1 in the genome-wide RNA transcript profile from TCGA (breast invasive carcinoma gene expression) using the RNAseq data set (TCGA_BRCA_exp_HiSeqV2-2015-02-24) in 1,009 tumor tissue samples from breast cancer patients.