STING1 and plasma cell myeloma: The different categories of innate immune signaling are grouped according to their pattern recognition receptors, which include (1) Toll-like receptors (TLR); (2) Nod-like receptors (NLR); (3) absent in myeloma (AIM2); (4) C-type lectin receptors; (5) retinoid acid-inducible gene I-like receptors (RIG I-like) and (6) cyclic GMP-AMP synthase (cGAS)/STING (stimulator of interferon genes) [1].