SLC1A5 and cancer: In other cancer cells, SLC1A5 and LAT1 rather play the role of “amino acid harmonizers,” rapid hetero-exchangers that maintain the optimal mix of all 20 proteinogenic amino acids in the cytosol (9), while Na+-amino acid co-transporters of the SLC38 family mediate net glutamine uptake to sustain glutaminolysis and proliferation (9).