KRAS and adenoma: However, based on Fearon and Vogelstein’s findings, the adenoma-carcinoma sequence describes a multi-step process for CRC development, promoted by specific and well-defined genetic aberrations of the genes APC (adenomatous polyposis coli), KRAS (GTPase KRas), DCC (Deleted in Colorectal Cancer) and TP53 (Tumor protein 53) [5].