The recombinant RBP4 protein expressed in the prokaryotic expression system, RBP4 protein standard (R&D) expressed in the eukaryotic expression system and natural RBP4 protein secreted by HCC cell lines could all react specifically and were more conducive to the accurate detection of RBP4, effectively avoiding false‐positive results. This evidence concerns the gene RBP4 and hepatocellular carcinoma.