As a result of a thorough study on many natural and semisynthetic ecdysteroids, we have recently reported that certain derivatives can significantly decrease the doxorubicin resistance of a multidrug resistant (MDR) mouse lymphoma cell line (L5178MDR) that has been transfected with the pHa MDR1/A retrovirus to express the human ABCB1 or P-glycoprotein, an ATP-binding cassette (ABC) transporter [7]. The gene discussed is ABCB1; the disease is lymphoma.