As we wanted to determine whether mTOR inhibition with rapamycin could arrest tumour growth in mice with late-stage disease, we compared treatment of KC PTEN mice, with treatment in Pdx1-Cre; KrasG12D/+; Trp53R172H/+ (KPC) mice,18 which are resistant to most therapies.19 Cohorts of KC PTEN and KPC mice were established, and animals monitored until they developed clinically detectable pancreatic tumours, at which point mice would normally be sacrificed within 1–3 days. This evidence concerns the gene PTEN and neoplasm.