These findings are consistent with those of a phase I clinical study where it was shown that 5/20 biopsies of human tumours demonstrated a 2 fold reduction in Ki-67 staining after 7 days Selumetinib treatment, that all biopsies demonstrated a reduction in pERK1/2 staining, that wild-type and KRAS/BRAF mutants showed similar levels of target inhibition and that mutant tumours were more sensitive to the growth inhibitory effects of the agent23. This evidence concerns the gene KRAS and neoplasm.