TPST1 and cancer: It is interesting to note that latent membrane protein 1 (LMP1), which is encoded by EBV, induces tyrosine sulfation of CXCR4 through upregulation of tyrosylprotein sulfotransferase-1 (TPST-1) and promotes metastasis of cancer cells (129), a mechanism that could also be applied to GPR15.