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Amino Acids are not only major nutrient sources, but also serve as chemical signals to control cellular growth. Rab1A recently emerged as a key component in amino acid sensing and signaling to activate the mTOR complex1 (mTORC1). In a recently published study [1], we generated tamoxifen-inducible, conditional whole-body Rab1A knockout in adult mice. These mice are viable but develop hyperglycemia and glucose intolerance. Interestingly, Rab1A ablation selectively reduces insulin expression and pancreatic beta-cell population. Mechanistically, branched chain amino acids (BCAA), through the Rab1A-mTORC1 complex, promote the stability and nuclear localization of Pdx1, a master transcription factor that controls growth, function and identity of pancreatic beta-cells. These findings reveal a role and underlying mechanism by which amino acids control body’s glucose level through a beta-cell specific function by the Rab1A-mTORC1-Pdx1 signaling axis, which has implications in both diabetes and cancer.