KRAS and colorectal carcinoma: When we sequenced multiple areas within paired samples, we found intra-tumor mutational heterogeneity in important CRC genes such as KRAS and SOX11. In some cases, these mutations were absent in the paired carcinoma, indicating the ability of adenomatous tissue to carry driver mutations that are either not inherited by the subsequent carcinoma or arise after carcinoma progression but remain within histologically defined adenomatous tissue.