Summary Through the funding opportunity described in PAR-20-272, this proposal seeks funds to purchase a fluorescence-detection HPLC (high-performance liquid chromatography) system to quantitatively assess stimulation-induced dynamic assembly of protein complexes in chemotactic signaling. The goals of the parent grant R35GM131768 are to investigate how cells sense extracellular chemical gradients and control their migration behaviors. First, we will determine how phosphorylated, GDP-bound RacE activates TORC2 to facilitate AKT phosphorylation at the leading end of migrating cells while GTP-bound RacE inhibits TORC2 at the trailing end. This will involve multiple experimental approaches, including cellular reconstitution using knockout cell lines, biochemical reconstitution of RacE-regulated TORC2 activity with purified proteins, protein interaction analyses at the single-molecule level in vitro, live imaging of cells, and structural analysis using X-ray crystallography. Second, we will decipher a key mechanism controlling human PTEN localization at the plasma membrane and nucleus. Third, we will determine the effects of the manipulation of PTEN localization on tumorigenesis in vivo using animal models.