Additional reports also suggest that PTX administration might increase the effectiveness of antitumor chemotherapy [7,8], and our previous studies demonstrated that PTX induced the reversal of vincristine (VCR) and/or adriamycin resistance in P-gp-positive L1210/VCR (P-gp positive cell variant of L1210 cells were obtained by selection with VCR) mouse leukemia cells [9,10]. The gene discussed is PGP; the disease is leukemia.