MKI67 and neoplasm: 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.