Given the fact that the ER stress inducer PERK was more expressed in breast cancer cells lacking STARD7, we also look at levels of other ER stress downstream targets such as Eukaryotic Initiation Factor 2α (EIF2α), X box‐binding protein 1 (XBP1) and Activating transcription factor 4 (ATF4). Here, XBP1 is linked to breast cancer.