In our study, DDK1 was one of the candidate indicators according to the GEO data analysis, by which the expression levels of DKK1 in HCC tissues were significantly higher than that in non-HCC tissues (Supporting Figure 1); however, in our first-step validation, we simply found a marginally higher median of DKK1 levels in the HCC population. Here, DKK1 is linked to hepatocellular carcinoma.