Fig 2: Docking of 2HF, DNPSG and ATP to RLIP76(A) Binding interaction of RLIP with 2HF was demonstrated by elution of recombinant RLIP with elution buffer containing 2HF. (B) shows binding modes of 2HF and DNP-SG at the R232 site. (C) 2HF forms a hydrogen bond with Q269 and cation-π interaction with K237. (D) DNP-SG forms hydrogen bond/salt bridge network with R232/S234/K268/N341. (E) ATP also prefers binding at the ATP-binding pocket of Rlip forming 5 H-Bonds to G235, K237, S265, K268 and R272. Details are given in the Materials and Methods section.

Fig 3: Comparative molecular biological characterization of parental and resistant cell lines. (A) ABCB1, RALBP1, and TOP2A gene expression in parental and resistant cell lines, cultured in the presence (+) or absence (−) of 2 µM doxorubicin. * p ≤ 0.05; ** p ≤ 0.01; *** p ≤ 0.001; **** p ≤ 0.0001. (B) Quantitative analysis of MDR1 and RALBP1 protein expression by Western blot. Asterisks indicate significant differences between parental and resistant sublines; * p ≤ 0.05; ** p ≤ 0.01; *** p ≤ 0.001; **** p ≤ 0.0001. (C) Western blot images of MDR1, TOP2A, and RALBP1; for ABCB1 quantification, the protein load per lane of the resistant cell lines was reduced to 1 µg, due to the extreme upregulation. (D) Metabolic activity of parental and resistant cell lines after exposure to increasing concentrations of doxorubicin for 72 h in the presence of the MDR1 inhibitor tariquidar.