DKK1 and non-small cell lung carcinoma: A heterogeneous expression level of DKK1 was evident among the NSCLC cell lines with the highest DKK1 mRNA expression found in A549 and H23 cells, which displayed an about 80- and 30-fold higher expression than that observed in the U-1810 cells, which were used for the gene expression profiling of residual clones (Fig. 4c, left panel).