Abstract One outcome of activation of the PI3K pathway is increased aerobic glycolysis, but the upstream signaling events that regulate the PI3K pathway, thus the Warburg effect, are elusive. Increasing evidence suggests that Plk1, a cell cycle regulator, is also involved in cellular events in addition to mitosis. To test whether Plk1 contributes to activation of the PI3K pathway, thus aerobic glycolysis, we have identified PTEN as a Plk1 substrate. We hypothesize that Plk1 phosphorylation of PTEN contributes to activation of the PI3K pathway and the Warburg effect. Our data show that overexpression of Plk1 leads to activation of the PI3K pathway and enhanced aerobic glycolysis. In contrast, inhibition of Plk1 causes markedly reduced glucose metabolism in mice. Mechanistically, we show that Plk1 phosphorylation of PTEN and Nedd4-1 results in PTEN inactivation. Finally, we show that Plk1 phosphorylation of PTEN promotes tumorigenesis in both its phosphatase-dependent and -independent pathways. Note: This abstract was not presented at the meeting. Citation Format: zhiguo li, li jie, Liu xiaoqi. Plk1 phosphorylation of PTEN causes a tumor-promoting metabolic state. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1133. doi:10.1158/1538-7445.AM2015-1133