In contrast to the existing GSH-sensitive NPs based on liposomes or hydrophilic nanocores, ours have hydrophobic nanostructures and a PDSA core, allowing the NPs to carry more drugs, especially J4 and Apa.39 With this method, it is now possible to reach the effective drug concentration of J4 and Apa in osteosarcoma stem-like/progenitor cells, so that the ER stress can exceed the threshold to induce cell apoptosis. Here, ENPEP is linked to osteosarcoma.