KRAS and neoplasm: First, we compared basal levels of p-ERK1/2 and found that there was no significant difference between wild type and KRAS/BRAF mutant tumours, either when mutants were analysed collectively (all mutations in the pathway) or when mutations were considered individually (i.e KRAS codon 12/13 and BRAFV600E) (Fig. 5a and Supplemental Fig. S3a).