Another strategy is to downregulate the expression of MDR‐related proteins by RNA interference, as siRNAs could help to treat drug resistance by reducing the protein levels of P‐gp, MRP1, and Bcl2.80, 81 However, directly administrating siRNA faces the obstacles of degradation and elimination by ribonuclease (RNase), poor permeability, and endosomal trapping, while nanocarriers could overcome those barriers for delivering siRNA to MDR cancer cells. Here, PGP is linked to cancer.