DKK-1 is a candidate gene for tumor suppressor in glioma and considered as a serologic and prognostic biomarker.In our recent study of 12 human glioma cell lines, we found that the supernatant fluid and lysate of 9 cell lines had high level of DKK-1 protein and the other 3 had very low level or non-detectable DKK-1 protein (Zhou et al, unpublished data). Here, DKK1 is linked to central nervous system cancer.