SMAD4 and colorectal carcinoma: Within the nodes of the circ-CCDC66-miRNA-mRNA network, two miRNAs (18.18%) have been associated with intestinal diseases40,41; nine mRNAs (accounting for 60%, including NR4A3 42, ARRB1 43, SMAD4 44, EPHA7 45, CCND1 46,47, and POLQ48) have been linked to the occurrence and development of CRC.