CD44 antibodies target a family of transmembrane glycoproteins involved in cell-cell interactions, adhesion, migration, and signaling. The CD44 receptor binds hyaluronic acid (HA) and other extracellular matrix components, playing roles in inflammation, wound healing, and cancer progression. Its structure includes a conserved N-terminal ligand-binding domain, a variable region generated by alternative splicing (resulting in multiple isoforms), and a cytoplasmic tail that interacts with cytoskeletal and signaling molecules. The standard isoform (CD44s) is widely expressed, while variant isoforms (CD44v) are tissue-specific and linked to pathological states, particularly tumor metastasis and stemness.
CD44 is a marker for cancer stem cells (CSCs) in various malignancies, where it promotes survival, drug resistance, and metastatic spread. Antibodies against CD44 are critical tools for detecting expression patterns in research and diagnostics, often via flow cytometry, immunohistochemistry, or Western blot. Therapeutic CD44 antibodies are explored to block pro-tumorigenic signaling or deliver cytotoxic agents to CSCs. However, functional complexity arises from isoform diversity, post-translational modifications, and context-dependent roles in different microenvironments. Some antibodies specifically recognize epitopes in variant regions, while others target conserved domains, influencing experimental outcomes. Despite challenges, CD44 remains a compelling target for understanding cellular plasticity and developing precision therapies.