Figure 3.

Multidrug resistance (MDR) assay in CML-T1 and CML-T1/IR cells and immunodetection of MRP2 protein by western blot analysis in the CML-T1 and CML-T1/IR cells compared with other cell lysates. (A) Measurement of calcein retention as a surrogate of MDR exporter activity in the CML-T1 and CML-T1/IR cells was performed as described in 'Materials and methods'. Cyclosporine A (CsA) and verapamil were used as inhibitors of MDR. No MDR activity was detected in the CMLT1 and CMLT1/IR cells as reflected by 100% calcein retention in the cells. (B) Cell lysates of CML-T1 and CML-T1/IR were subjected to SDS-PAGE and western blot analysis for immunodetection of MRP2 together with the lysates of K562, HL-60, HeLa cells and mouse liver tissue, which were used as MRP2 positive controls.