In experiments aimed at investigating whether the rate of release of chemotherapeutic drugs from multidrug resistant human prostate cancer cells was affected by the continued presence of the P-gp inhibitor, compound 29 [14, 15] (Fig 1D), we first exposed DU145TXR cells [21] to daunorubicin in the presence of compound 29 to enable the cells to significantly accumulate the chemotherapeutic. Here, PGP is linked to prostate carcinoma.