SLC7A5 encodes LAT1 (L-type amino acid transporter 1), a heterodimeric membrane transporter complex that functions with SLC3A2 (4F2hc) to transport large neutral amino acids, particularly leucine, across cell membranes in a sodium-independent manner 1. The transporter operates as an antiporter, facilitating amino acid exchange and maintaining intracellular amino acid levels essential for protein synthesis and cellular growth 2. Mechanistically, SLC7A5 supports mTORC1 signaling activation through leucine uptake, promoting cell proliferation and growth 3. The protein exhibits cancer-specific expression patterns, being highly upregulated in various tumor types where it supports enhanced glutamine and amino acid metabolism required for rapid cancer cell growth 4. In colorectal cancer with KRAS mutations, SLC7A5 is critical for maintaining the increased glutamine consumption that supports enhanced proliferation 2. Under arginine-limited conditions, SLC7A5 functions as a high-affinity citrulline transporter, enabling cancer cells to synthesize arginine from citrulline 5. The transporter's cancer-specific expression and essential role in tumor metabolism make it an attractive therapeutic target, with specific inhibitors like JPH203 showing promise in clinical trials for cancer treatment 4.