Studies show that sphingosine-1-phosphate receptor 3 (S1P3) is over-expressed in invasive breast cancer cell lines, resulting in an increase in the expression of COX-2 and in microsomal prostaglandin (PG) E2 synthase, accompanied by a high synthesis of PGE2 and favoring tumor metastasis [121]. This evidence concerns the gene S1PR3 and breast cancer.