Figure 4. RGR-d and syntaxin-4 in the plasma membrane of cultured human fetal RPE cells. Polarized human fetal RPE cells from a single donor were cultured in replicate chamber wells. The cells were fixed and incubated with (A) DE21 and (B) anti-syntaxin-4 antibodies. Immunofluorescence was detected with secondary antibodies conjugated to FITC or Cy3, respectively. C: Both RGR-d and syntaxin-4 were detected at the cell borders (arrowheads). The merged image shows close juxtaposition but little co-localization of these two membrane proteins. Scale bar, 10 μm.