The cytoskeleton-associated protein 4 (CKAP4), also known as CLIMP-63 or ERGIC-53. is a transmembrane protein primarily localized to the endoplasmic reticulum (ER) and Golgi apparatus. It plays a role in maintaining ER structure, vesicular trafficking, and cytoskeleton organization by interacting with microtubules. CKAP4 has gained attention due to its dual presence in intracellular membranes and the cell surface under certain conditions, where it functions as a receptor for extracellular ligands like Dickkopf-1 (DKK1) and surfactant protein A (SP-A).
CKAP4 antibodies are tools used to study its expression, localization, and functional roles. Research highlights CKAP4's involvement in cancer progression, as its overexpression in tumors (e.g., lung, gastric, and pancreatic cancers) correlates with poor prognosis. Surface CKAP4 interacts with growth factor receptors (e.g., EGFR, VEGFR2), promoting oncogenic signaling, metastasis, and chemoresistance. Antibodies targeting extracellular CKAP4 domains have shown potential in blocking these interactions, suggesting therapeutic applications.
Additionally, CKAP4 antibodies are utilized in diagnostic research, as secreted CKAP4 is detectable in blood and may serve as a biomarker for early cancer detection. However, CKAP4's roles remain context-dependent, with some studies indicating tumor-suppressive effects in specific cancers. Ongoing work aims to clarify its mechanisms and validate antibody-based strategies for clinical translation.