PGP and neuroblastoma: Further, the work of Sietsma et al. [45] demonstrated that PDMP decreased paclitaxel and vincristine efflux in neuroblastoma cells, thus acting as a P-gp antagonist, and Plo et al. [22] showed that D-threo-PDMP increased rhodamine retention and acted as a chemosensitizer in P-gp expressing AML cells, including KG-1a.