This is compounded by the observation that in soft tissue sarcoma models, GCN2 KO phenotypes can be largely compensated by PERK maintaining ATF4 signalling [28] — in order to completely ablate eIF2α phosphorylation upon ISR activation it is necessary to KO both GCN2 and PERK [29]. This evidence concerns the gene EIF2AK3 and soft tissue sarcoma.