SMAD4 and colorectal carcinoma: The most relevant mechanisms of CRC carcinogenesis identified to date include genetic chromosomal instability, microsatellite instability, serrated neoplasia, specific gene signatures, and specific gene mutations, such as APC (Adenomatous Polyposis Coli), SMAD4 (SMAD Family Member 4), BRAF (v-raf murine sarcoma viral oncogene homolog B), or KRAS (Kirsten rat sarcoma viral oncogene homolog).