XBP1 and melanoma: In a subsequent investigation on melanoma, it was discovered that the MHC class I polypeptide-related sequence A/B (MICA/B) - the cognate ligands of major NK activating receptor NK group 2 member D (NKG2D), is negatively regulated by ER stress-associated IRE1/XBP1 pathway in human melanoma cell lines (Obiedat et al., 2019).