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. 2013 Apr 15;123(5):2119–2130. doi: 10.1172/JCI65425

Figure 6. ATP11B, STX6, and VAMP4 contribute to cisplatin export.

Figure 6

(A) Coimmunoprecipitation of ATP11B with STX6 or VAMP4 in A2780-PAR and A2780-CP20 cell lysates. All coimmunoprecipitation lanes were run on the same gel but were noncontiguous. Input lanes (1:10 of original cell lysate) were run on a second gel simultaneously and detected with anti-ATP11B. Association of ATP11B with STX6 or VAMP4 was stronger in the presence of 0.5 μM cisplatin. Densitometry analysis of ATP11B protein was performed with ImageJ software. Data were normalized to a loading control (β-actin from original lysate) and are representative of 2 independent experiments. (B) Time course of cisplatin efflux in STX6- or VAMP4-silenced A2780-PAR cells and (C) STX6- or VAMP4-downregulated A2780-CP20 cells. Silencing of STX6 in A2780-CP20 cells resulted in significantly increased cellular platinum contents after 10 to 30 minutes of incubation without cisplatin (*P < 0.05). (D) Time kinetics of cisplatin efflux in ATP11B-upregulated STX6- or VAMP4-downregulated A2780-PAR cells and (E) in ATP11B-upregulated STX6- or VAMP4-silenced A2780-CP20 cells. Percentages of remaining cellular platinum were significantly increased in ATP11B-upregulated VAMP4-silenced A2780-PAR cells at all time points compared with those in A2780-PAR ATP11B-upregulated cells. In contrast, in ATP11B-upregulated A2780-CP20 cells, downregulation of STX6 led to increased platinum contents at all time points compared with those of ATP11B-upregulated A2780-CP20 cells. Data represent the mean ± SEM. *P < 0.05.