EIF2AK3 and breast neoplasm: Furthermore, our findings on ERO1‐deficient breast tumours suggest that ISRIB restrains the growth of tumours with high PERK and a low load of protein translation/low ERO1, possibly because the rapid ISRIB‐dependent increase in protein translation results in a toxic action in cells deficient in an enzyme with protein folding activity, hence, with impaired proteostasis (Figure 7).