MTOR and neoplasm: Despite our observation that the Ras/MEK/ERK compensatory pathway is activated in primary cells following the PI3K/AKT/mTOR inhibition, the ex vivo treatment of the PDX with a combination of KU-0063794 (mTOR inhibitor) and AZD7328 (AKT inhibitor) showed an effective reduction in tumour outgrowth.