STING1 and plasma cell myeloma: The innate immune signalling structures, the so called innate immune sensors, include Toll-like receptors (TLRs), Nod-like receptors (NLR), absent in myeloma (AIM2), C-type lectin receptors, retinoid acid-inducible gene I-like receptors (RIG I-like) and cyclic GMP-AMP synthase (cGAS)/STING (stimulator of interferon genes) [26,27].