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Fig. 2 | Cancer Cell International

Fig. 2

From: Inhibition of the PI3K but not the MEK/ERK pathway sensitizes human glioma cells to alkylating drugs

Fig. 2

GBM cell lines show high intrinsic tolerance to alkylating cytostatics cisplatin and TMZ. a Cisplatin resistance status of U87, U251, and U373 cell lines was assessed by MTT assays (n = 4). b Intrinsic resistance of GBM cell lines is demonstrated in comparison to cell pairs of non-resistant and cells with acquired resistance. GBM cell line IC50 concentrations of cisplatin parallel the ones of resistant MCF-7 breast-, and A2780 ovarian cancer cell lines (determined by MTT assays; n = 3). c GBM cell lines were treated by weekly cycles of cisplatin and IC50 values were assayed after each treatment cycle in MTT assays. IC50 values were obtained from sigmoidal concentration–response curves and dotted in a time-dependent manner. d Western blots showing MRP-2 and P-gp expression in GBM cell lines untreated and after 24 cycles of weekly intermittent cisplatin exposure. β-actin Western blot was performed to control for loading. e TMZ resistance status in U87, U251 and U373 cells was assessed by MTT assays (upper graph; n ≥ 6). The respective IC50 values for each cell line are shown in the table below the graph

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