<qa>  What is the dose escalation study performed in three steps?Investigating the safety and the activity of Rapamycin, administered before and during preoperative radiotherapy in patients with an operable colorectal carcinoma. The phase I dose escalation study will be performed in three steps 2, 4 and 6 mg. Patients entered in phase II will follow the same tolerable treatment regimen as patients in phase I study. 