Interestingly, GSH has been shown to facilitate drug export mediated by the MRP proteins in tumor cells.35, 36, 37 Moreover, GSH can stimulate the ATPase activity of MRP1,38 and GSH can also form drug conjugates that are exported.39, 40 There is no evidence to date that doxorubicin or taxol can form conjugates with GSH, but MMC is known to conjugate with GSH.41 For this reason, CAF could potentially stimulate export of doxorubicin and taxol as unmodified drugs and MMC as a GSH–MMC conjugate. This evidence concerns the gene DNAH8 and neoplasm.