PITPNM3 and breast carcinoma: CCL18 produced by breast tumor-associated macrophages was shown to be involved in breast cancer metastasis via the interaction and signaling through PITPNM3/Nir1, which was pertussis toxin (PTX) dependent, despite the fact that PITPNM3/Nir1 does not show apparent structural or functional similarity to conventional GPCRs (8).