ATF4 and breast carcinoma: LMPt enters the cell mainly through caveolin-mediated endocytosis, and then fuses with endosomes and lysosomes to deliver MPt to mitochondria and the endoplasmic reticulum to induce mitophagy based on the fusion of lysosomes and mitochondria, and endoplasmic reticulum stress and subsequent apoptosis via the Bip-PERK-eIF2α-ATF4 axis to exert an anti-breast cancer effect.