MTOR and neoplasm: mTOR, a key downstream effector pathway of RAS35,36 involved in cell growth and protein synthesis,35,36 was strongly reduced in both KPC;KhkC−/− and KPC;KhkA/C−/− tumors, as shown by reduced expression of phospho-RPS6 in immunoblot analysis and by immunofluorescence staining of mouse tumor cells treated with mTOR inhibitor rapamycin, as well as from mouse tumor tissue sections (Figures 5D, 5E and S5C).