To further investigate the mechanisms at the basis of the down-regulation of the doxorubicin-induced Pgp transcription, we focused on three interconnected events elicited by doxorubicin in cancer cells and involved in Pgp up-regulation: The increase in intracellular ROS, and the activation of the transcription factors HIF-1α and NF-kB. Here, NFKB1 is linked to cancer.