In the neutralization assay, we found that the INSL5 peptide contributed to NPC cell proliferation and invasion, while an anti‐INSL5 monoclonal antibody (αINSL5, 50 and 100 μg/ml) could reverse the peptide‐induced proliferation (Fig 6A) and invasion (Fig 6B) in a dose‐dependent manner. This evidence concerns the gene INSL5 and nasopharyngeal carcinoma.