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Figure 4: MRP4 expression is relevant to reduce aspirin toxicity. Cell death in Hek-293 transfected cells (MRP4 cells). pCDNA3.1 transfected cells were used as control (pCDNA3.1). Aspirin toxicity was evaluated after 24 h aspirin (5 mM) treatment, with trypan blue exclusion test. (a) Multidrug resistance protein-4 (anti-MRP4) expression in Hek-293 cell lines is shown in the first lane (PCDNA 3.1); MRP4 transfected cultures are shown in the second lane (MRP4). A representative experiment, of 3 performed, is presented. (b) Expression of “trypan blue-not excluding” cells is evaluated as percentage of cell death in aspirin treated cells (5 mM) compared with control cells. Data were reported as mean ± SD of 3 experiments performed (NS: not significant). (c) Dead cell profiles, representative flow cytometry histograms of Hek-293 cells stained with 7-AAD, out of three performed experiments. The panel represents pCDNA3.1 and MRP4 transfected cells. Numbers in histograms indicate percentage of 7-AAD+ cells. (d) Ratio of the total numbers of 7-AAD+ cells in 5 mM aspirin treated versus matched untreated cells, both in pCDNA3.1 and in MRP4 transfected cells. Data were reported as mean ± SD of 3 experiments performed; indicates significant differences in aspirin samples of pCDNA3.1 versus MRP4.