ERN1 and breast cancer: Furthermore, we recently reported that RIDD activity is readily induced in wild type but not in Ern1‐conditional knock‐out bone marrow‐derived macrophages treated with the CM of ER‐stressed tumor cells, and IRE1α but not PERK predicts CD274 (PD‐L1), a gene under regulation miR‐34a itself a RIDD target (Upton et al, 2012), in macrophages isolated from human endometrial or breast cancers (Batista et al, 2020).