This ELISA kit enables quantitative detection of RAN, a GTP‑binding nuclear transport protein released as a CHO host cell impurity. RAN plays a key role in nucleocytoplasmic trafficking, and its presence in biologics can indicate incomplete purification. The assay provides high sensitivity and strong specificity for monitoring RAN across upstream and downstream samples. With a pre‑coated microplate and optimized reagents, E‑65RAN supports regulatory‑aligned HCP profiling, process validation, and impurity clearance studies.