LGR5 and cancer: GPCRs such as CXCR4, LPAR, PAR1, LGR5, and S1PR are up-regulated in many advanced cancers and induce invasion and metastasis [11], while CXCR4 [12], CXCR1/2 [13] and LGR5 [14] have been linked to TIC-like phenotypes.