SMAD4 and colorectal carcinoma: CRC - colorectal cancer; SMAD4 - Mothers against decapentaplegic homolog 4; IBD - inflammatory bowel disease; HDL-C - high-density lipoprotein cholesterol; EMT - epithelial-to-mesenchymal transition; SBO - small bowel obstruction; LDL - low-density lipoprotein