Inhibition of radiation induced mTOR phosphorylation enhances antitumor efficacy of radiotherapy in vivo . Four groups of Nu/Nu nude mice (n=10) with PANC-1 xenografts were treated as indicated. After 21 days treatment, the mice were sacrificed and the tumors were removed. (A) The tumor volumes from the same group mice were presented as mean ± SD and statistically analyzed. *, P < 0.05 and **, P < 0.01 vs. control and #, P < 0.05 and ##, p < 0.01 vs. radiation treatment alone. (B) The xenografts were embedded in paraffin blocks and paraffin sections were examined by immunohistochemistry using p-mTOR antibody. (C) Apoptosis in tumor tissues was analyzed by TUNEL assay using Tumor TACSTMIn Situ Apoptosis Detection Kit. TUNEL positive cells were counted for every 1000 cells from ten areas of each slide, and three different slides were analyzed for each sample. Data represents as mean ± SD, **, P < 0.01 vs. IR treatment alone.