Desmoglein 1 is reduced in melanoma-adjacent keratinocytes in human epidermis. (A) Paraffin-embedded sections of benign nevi and primary-stage melanoma were costained for Dsg1 or Ecad and Mel-A to highlight cadherins at cell–cell interfaces of keratinocytes surrounding pigmented cells. The dashed line indicates basement membrane. (B–E) Both distant (two to four cells away) and proximal keratinocytes were examined for cadherin staining for quantification. Pixel intensities were determined for four benign and 12 melanoma samples and the ratio of proximal to distant intensities plotted. A significant decrease in Dsg1, but not Ecad, intensity proximal to the melanoma lesions was observed. (Note that the melanoma sample in the bottom panel was also used in Fig. 5 A where E-cadherin fluorescence intensity was correlated with the extent of melanoma cell spread.) Mean ± SEM depicted. **P < 0.01. Student’s t test.