S1PR1 and breast carcinoma: Experimental evidence implicated S1PR1 coupled to Gi and persistently triggered STAT3, mitogen-activated protein kinase (MAPK) and AKT signaling pathways, to promote many types of tumor growth and metastasis including breast cancer (Lee et al., 2010; Deng et al., 2012; Paik et al., 2014; Go et al., 2015).