CD98 (SLC3A2/4F2 heavy chain) is a transmembrane protein that belongs to the solute carrier family. CD98 forms heterodimeric complexes with various amino acid transporters such as LAT1 and LAT2 and regulates uptake of amino acids. CD98 is an early expressed antigen on the surface of activated human lymphocytes, and is also expressed in most cell types with the exception of platelets. CD98 is highly expressed in the tubules of the kidney and the gastrointestinal tract. CD98 also expressed in tumors, including glioma, ovarian cancer, and astrocytomas. Expression of CD98 has been implicated in tumor progression and correlates with poor outcome in patients with pulmonary neuroendocrine tumors. CD98 is also involved in integrin trafficking through association with β1 and β4 integrins, and regulates keratinocyte adhesion and differentiation. Thus, CD98 is a widely expressed transmembrane protein involved in amino acid transport, integrin function, and differentiation.
