The day 2 versus pre-treatment dynamic PET scans showed that there was no significant difference in [18F]-FLT tumour uptake in HCT116 xenograft-bearing mice treated with drug vehicle or with either single agent, whereas there was a significant decrease in [18F]-FLT tumour uptake after PI3K/MEK inhibitor combination treatment, which correlated with the enhanced efficacy observed later in the study. The gene discussed is MAP2K7; the disease is neoplasm.