CXCR4 and plasma cell myeloma: The SMO antagonist vismodegib has recently been FDA-approved in basal cell carcinoma [37] and several molecules targeting GPCRs are in clinical trials as adjuvants of chemotherapies (namely Bosentan, an Endothelin A/B subtype receptor antagonist for melanoma or BKT140, a CXCR4 antagonist for multiple myeloma).