This hypothesis is in keeping with other studies reporting that ligands of PBR like PK11195 and Ro 5-4864 (Carmel et al, 1999), and of PAFR such as SDZ 62-434 (Brunton and Workman, 1993) and CV 3988 (Bussolati et al, 2000) inhibited breast cancer cell proliferation at micromolar levels which are not consistent with high-affinity ligand-receptor binding. This evidence concerns the gene PTAFR and breast cancer.