As discussed before, the cancer stem cell-specific–targeted mesoporous silica (mSiO2)-dendritic polyglycerol (dPG) nanocarriers co-delivered the chemotherapy drug DOX and the P-gp inhibitor tariquidar (Tar) for reversing MDR and enhancing chemotherapy to breast cancer stem cells (Pan et al., 2021). Here, PGP is linked to cancer.