IL1B and plasma cell myeloma: To confirm in vivo that IL-1β can be one of the key –although indirect– drivers of NF-κB activation in myeloma cells, 4 groups of 5 mice each were engrafted with MM.1S cells as described previously and left either untreated or treated for 3 h with TNF-α or IL-1β, or treated with Anakinra (IL1ra), a selective IL-1β inhibitor, for 24 h.