DKK3 and squamous cell carcinoma: The heatmap image of messenger RNA (mRNA) expression of REIC/Dkk-3 gene from the UCSC Cancer Genome Browse, which is freely available public database (https://genome-cancer.ucsc.edu/) (we downloaded the data on July 16 2013), showed that REIC/Dkk-3 gene expression was reduced in majority of examined samples of both lung adenocarcinomas and squamous cell carcinomas compared with normal lung tissues (Figure S1).