KRAS and colorectal cancer: Unfortunately all of the cases with an EGFR mutation also had a KRAS mutation and it has been observed in colorectal cancer (although inconclusive in NSCLC) that a high frequency of KRAS mutations limits the benefits of EGFR inhibitors [30] as it leaves the KRAS protein turned “on” and signalling within the cancer cell continues regardless of the fact that the EGFR receptor is blocked.