V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog also known as KRAS is a protein which in humans is encoded by the KRAS gene. Like other members of the Ras family, the KRAS protein is a GTPase and is an early player in many signal transduction pathways. KRAS is usually tethered to cell membranes because of the presence of an isoprenyl group on its C-terminus.

Pivotal studies indicate a role of excision repair cross-complementation 1 (ERCC1) gene and ribonucleotide reductase M1 (RRM1) gene in conferring a differential sensitivity to cytotoxic chemotherapy and epidermal growth factor receptor (EGFR) gene has been recently extensively investigated in non-small-cell lung cancer (NSCLC).

V-raf murine sarcoma viral oncogene homolog B1, also known as BRAF, is a protein which in humans is encoded by the BRAF gene. The BRAF gene makes a protein called B-RAF, which is involved in sending signals in cells and in cell growth. This gene may be mutated (changed) in many types of cancer, which causes a change in the B-RAF protein. This can increase the growth and spread of cancer cells.