In addition to powering function and proliferation of GBM cells, intracellular ATP concentrations drive drug resistance.174 Zhu et al. overloaded the GBM mitochondria with Ca2+ to induce cell apoptosis (Fig. 6C).175 The authors fabricated CaCO3 NPs loaded with catalase, Ce6, and buthionine sulfoximine (BSO) to combine oxygen and GSH depletion with calcium overloading. Here, CAT is linked to glioblastoma.