(A) Analysis of cadherin localization within desmosomes. Structured illumination microscopy (SIM) is able to resolve the distance from plaque to plaque when desmosomes are stained with a C-terminal DP antibody and an N-terminal cadherin antibody, as shown in the example SIM image (Figure 3A). Desmosomes were defined by regions of parallel DP staining, or ‘railroad tracks’. DP (green) and cadherin (either Ecad or Dsg2, red) fluorescence intensity were measured within the desmosome region of interest (black rectangle). (B) Representative images of desmosomal regions in human keratinocytes cultured in high Ca2+ media for 1, 3 or 18 hr as indicated. Images are oriented with cell border horizontal. Scale bar, 0.5 µm. (C) Quantification of cadherin (Ecad or Dsg2) levels relative to DP in desmosomes at different time points after initiation of desmosome assembly with high Ca2+ culture conditions. AU, arbitrary units. Means ± SE, n = 25 desmosomes, *p<0.05.