Fig. 6. Immunofluorescence analysis confirms that SNX2-suppression does not grossly perturb retrograde endosome-to-TGN transport of FITC-STxB. (A) FITC-STxB-uptake-assay (performed as described in Materials and Methods). Cells were fixed after 30 minutes and immunolabeled for SNX2 (Alexa633, red channel) and SNX1 (Alexa594, magenta channel). (B) After FITC-STxB internalization for 30 minutes in SNX2-suppressed cells, the toxin colocalized intensively with TGN46 (Alexa594, red channel); yellow in the merged image. (C) Colocalization analysis of STxB and TGN46 of confocal image sections using MetaMorph (see Materials and Methods for further details) in control cells (37±0.4%) and SNX2-suppressed cells (40±8%); s.d. determined from mean for individual visual fields for n>50 cells. Values are given as the mean ± standard deviation (s.d.); bars, 20 µm.