SPNS2 and metastatic melanoma: An additional clue for the involvement of Spns2 in the induction of metastasis was provided by the study in mice models of metastatic melanoma with Spns2 knockout that exerted low rate of metastasis formation in lung nodules accompanied by enhanced immune defence [12], which is in line with the role of S1P as a regulator of immune response, inflammation, angiogenesis and lymphomagenesis to promote cancer metastasis [40,41,42].