PGP and leiomyosarcoma: Of note, in both liposarcoma and leiomyosarcoma, the addition of propranolol to doxorubicin further increased the expression of P-gp on the plasma membrane; nonetheless, as reported by other authors37, it strongly inhibited the P-gp-mediated efflux of doxorubicin from the cells, thus resulting in an increase in the intracellular retention and effectiveness of doxorubicin31.