KRAS and colorectal neoplasm: To the best of our knowledge, this is the first study to propose and test a hypothetical model of intratumoral and intertumoral clonal evolution of the most frequently altered genes (KRAS, NRAS, PIK3CA and BRAF), comparing the mutational status in liver metastases, lymph node metastases versus paired primary colorectal tumors, using low-resolution arrays.