APC and colorectal carcinoma: The molecular signatures governing CRC occurrence and progression can mainly be grouped into three categories: (1) Genomic instability induced by inactivation of tumor suppressors (APC, TP53, SMAD4) or activation of proto-oncogene KRAS; (2) Microsatellite instability (MSI) caused by abnormal DNA mismatch repair (MMR); (3) Abnormal transcription due to hypermethylation in CpG islands [149,150,151,152].