SMAD4 and colorectal carcinoma: The mutation frequencies of TP53 were 82, 53, 55, 56, and 43% across five CRC populations; 55, 42, 44, 51, and 28% for KRAS; 20, 20, 15, 31, and 21% for SMAD4; and 12, 14, 15, 24, and 10% for PIK3CA. The high frequencies of these five driver genes confirmed their core roles in the progression of CRC.