PGP and cancer: Based on prior art evidence already demonstrating the effect of chitosan in improving the absorption and targeting of chemotherapeutic agents, overcoming the P-gp efflux barrier, combined with the findings of this study showing an additive effect of HPMCP to enhance the MTX internalization in glioblastoma cells, this study can be a starting point for biomolecular and formulation scientists to explore HPMCP as a functional and safe excipient to improve cancer cell targeting of chemotherapy P-gp substrate drugs.