Rapamycin decreases PD-L1 expression in lung tumors in vivo. Rapamycin decreases PD-L1 expression in lung tumors in vivo. Immunohistochemical staining for pS6 or PD-L1 in lung tumors treated with vehicle or rapamycin from A/J mice exposed to the tobacco-carcinogen NNK (A), C57BL/6 KRAS LA2 mice (B), or dox-exposed FVB mEGFR+/CC10+ littermates (C). Bar graphs quantify decreased staining of pS6 and PD-L1. Scale bar, 10 μm. *, P ≤ 0.05 by unpaired Student t test. Kristin J. Lastwika et al. Cancer Res 2016;76:227-238 ©2016 by American Association for Cancer Research