SMAD4 and cancer: The host genes of differentially expressed circRNAs were mainly associated with superpathway of inositol phosphate compounds, FoxO signaling pathway, valine degradation, etc. Notably, the host genes of differentially expressed circRNAs were associated with important CRC-related pathways, such as Deleted in Colorectal Carcinoma (DCC) mediated attractive signaling, Netrin-1 signaling, Loss of Function of SMAD2/3 in Cancer, SMAD2/3 MH2 Domain Mutants in Cancer, TGFBR1 LBD Mutants in Cancer, SMAD4 MH2 Domain Mutants in Cancer, and Loss of Function of SMAD4 in Cancer.