SLC7A2 is a low-affinity, high-capacity cationic amino acid transporter that mediates uptake of L-arginine, L-lysine, L-ornithine, and L-homoarginine across the plasma membrane 1. Beyond basic amino acid transport, SLC7A2 functions as a nutrient sensor coupling amino acid availability to cellular proliferation through mTORC1 signaling activation 23. In pancreatic islets, SLC7A2 is the predominant cationic amino acid transporter in α cells and is essential for arginine-stimulated glucagon secretion and α cell proliferation 3. SLC7A2 expression also regulates β and δ cell proliferation in response to interrupted glucagon signaling via mTORC1-dependent mechanisms 2. Genetic variants in SLC7A2 associate with HbA1c levels 3. In cancer, SLC7A2 acts as a tumor suppressor. Lower SLC7A2 expression correlates with enhanced multidrug resistance, reduced immune infiltration, and worse prognosis in non-small-cell lung cancer, ovarian cancer, and hepatocellular carcinoma 456. SLC7A2 promotes anti-tumor immunity by facilitating lysine catabolism-driven histone crotonylation, which enhances type I interferon signaling and CD8+ T cell infiltration in glioblastoma and triple-negative breast cancer 17. Conversely, SLC7A2 upregulation in pancreatic ductal adenocarcinoma promotes mTORC1 activation and metastasis 8.