许多肿瘤组织细胞中有Rho-123(一种带阳性电荷的氧杂蒽染料)的选择性滞留和细胞毒性。当两种细胞类型较长期暴露于Rho-123时,仅癌细胞生长受抑或被该药物杀死。某些肿瘤和正常细胞之间不同的Rho-123滞留有可能用来进行癌症临床治疗,然而其不同滞留和选择性毒性的基础仍不清楚。为了决定肿瘤中已发现的Rho-123选择性是否与MDR的存在有关,作者采用RT-PCR和毒性检测 Many tumor tissue cells have selective retention and cytotoxicity of Rho-123, a positively charged xanthene dye. When the two cell types are exposed to Rho-123 for a longer period of time, only cancer cell growth is inhibited or killed by the drug. Different Rho-123 retention between certain tumors and normal cells may be used for clinical treatment of cancer, however, the basis for their different retention and selective toxicity remains unclear. To determine if the Rho-123 selectivity found in tumors is related to the presence of MDR, the authors used RT-PCR and toxicity assays.