PITPNM3 and nasopharyngeal carcinoma: CCL18 is mainly produced by M2 TAMs, which has been reported to promote cancer metastasis via binding to its receptor Nir1 (also named PITPNM3) in multiple human malignancies including breast carcinoma [12], hepatocellular carcinoma [41], ovarian cancer [42], nasopharyngeal carcinoma [43] and lung cancer [44] etc. Therefore, we used neutralizing antibody to block the binding of CCL18 to its receptor Nir1.