Figure 4.

The role of ABCB4 in the modulating efflux of [¹⁸F]-D4-FCH. (A) The immunoblots of PC-3 and MDA-MB-231 cells following the CoCl₂ treatment. (B) Immunofluorescence: DNA stained by DAPI (blue) and cytoskeleton staining by phalloidin (red) and co-stained with ABCB4 (green). (C) The workflow of the efflux assay of [¹⁸F]-D4-FCH. The cells were pretreated with efflux inhibitors ABCB1 (1 µM zosuquidar), ABCG2 (3 µM ko143), or ABCB4 (10 µM cys A) for 1 h in a coincubation with 0.37 MBq [¹⁸F]-D4-FCH under the standard conditions. (D) Efflux assay; the method was described in B. (E) Immunoblots of the ABCB4 knockdowns. Upper, immunoblots of the PC-3 and MDA-MB-231 cells. Lower, densitometry. (F) Efflux activity of the radiolabelled choline species of the ABCB4 knockdowns from E.