DOCK4 and cancer: Through differential gene-expression analysis and Venn diagram analysis of mRNAs and host genes of circRNAs, we found eight genes in common: in which four gene are tumor-related, including Dock4, Fmr1, Zfhx3, Ralb. These genes have been reported in cancers or tumors in human [34, 37–39].We characterized circRNA catalogs in chickens, compared them with mRNAs and lncRNAs and found that in chickens, circRNAs have relatively shorter transcripts and similar GC content, these characteristics are similar to lncRNAs in chicken in our previous study [46].