TFE3 is a master transcriptional regulator of lysosomal biogenesis and autophagy that functions downstream of mTORC1 signaling 1. Under nutrient-rich conditions, mTORC1-mediated phosphorylation promotes TFE3 cytoplasmic retention and inactivation, while starvation or lysosomal stress leads to TFE3 dephosphorylation and nuclear translocation 1. TFE3 recognizes and binds E-box and CLEAR-box sequences to activate lysosomal gene expression 1. Additionally, AMPK phosphorylates TFE3 on serine residues to enhance its transcriptional activity during metabolic stress, creating a dual regulatory mechanism where mTORC1 controls subcellular localization while AMPK modulates transcriptional function 1. Clinically, TFE3 is highly relevant in cancer biology through chrX translocations that create oncogenic fusion proteins. TFE3 translocations drive aggressive renal cell carcinomas (tRCC) and perivascular epithelioid cell tumors (PEComas), with ASPSCR1-TFE3 fusions associated with particularly poor outcomes 23. These fusion proteins form liquid-like condensates that enhance transcriptional activity, alter chrX accessibility, and drive tumor progression 4. Notably, TFE3-rearranged PEComas show association with prior chemotherapy exposure and demonstrate resistance to mTOR inhibitor therapy, highlighting the clinical importance of understanding TFE3 dysregulation in cancer 3.