mTORC2 modulates c-Myc/miR-9-3p/E2F1 to promote survival in tumor xenografts and a mouse genetic model. (A and B) Images (A) and tumor growth curves (B) of MDA-MB-231 xenografts in BALB/c nude mice treated with vehicle, rapamycin, or PP242 daily by gavage. Treatment groups comprised five mice each. Each data point signifies the estimated tumor areas. Bar, 1 in. (C) Tumor weights of MDA-MB-231 xenografts in nude mice treated with vehicle, rapamycin, or PP242. (D) MDA-MB-231 xenografts were subjected to TUNEL labeling, with the percentage of apoptotic cells calculated under a light microscope. ***, P < 0.001 for comparison of PP242 therapy versus control therapy. Bars, 50 µm. (E and F) MDA-MB-231 xenografts were analyzed for expression of the indicated proteins via Western blotting (E) or miR-9-3p via RT-qPCR (F). (G–J) B lymphocytes from mice conditionally deficient in the Rictor gene were harvested and analyzed for cell death rate with Annexin V labeling (G) and trypan blue staining (H), expression of miR-9-3p with RT-qPCR (I), or cleavage of PARP and expression of c-Myc and E2F1 using Western blotting (J). The figures shown are from a single representative experiment out of three repeats. Error bars represent mean values ± SEM.