CD98 (Cluster of Differentiation 98) is a heterodimeric transmembrane glycoprotein composed of a heavy chain (CD98hc, encoded by SLC3A2) and a light chain (e.g., LAT1, encoded by SLC7A5), connected by disulfide bonds. It is widely expressed in various cell types, including immune cells, epithelial cells, and tumor cells. Functionally, CD98 is primarily involved in amino acid transport, particularly the transmembrane movement of neutral amino acids, which are essential for cell proliferation and metabolism. Additionally, CD98 interacts with integrin β1 to regulate cell adhesion, migration, and signaling. In the immune system, it plays a role in lymphocyte proliferation and activation, as well as in inflammatory responses. In pathological contexts, CD98 is highly expressed in various cancers and is associated with tumor invasion, metastasis, and drug resistance. For example, in extranodal natural killer/T-cell lymphoma (ENKTL), CD98 enhances chemoresistance via exosome-mediated mechanisms. High expression of CD98 in solid tumors is also linked to poor prognosis and may serve as a biomarker for tumor progression and treatment response. Given its critical role in tumor metabolism and signaling, CD98 has emerged as a potential therapeutic target for cancer.