Reduced epidermal PAR3 and increased P-cadherin levels at heterologous contacts correlate with progression of human melanoma. (A) H&E staining (top) and PAR3 and TRP2 immunostainings (bottom) of human normal skin and melanoma tissue. Bars: (top) 100 µm; (bottom) 20 µm. Data are representative of at least three independent experiments. (B) Quantification of epidermal anti-PAR3 immunoreactivity in normal skin epidermis (n = 10 tissues from different donors), melanoma with tumor depth ∼1 mm (n = 9 tumors from different patients), and melanoma with tumor depth ∼10 mm (n = 8 tumors from different patients). Data are mean + SEM. *, P = 0.0113; **, P = 0.0040; one-way ANOVA with Tukey posthoc test. (C) P-cadherin and TRP2 costaining in melanoma in situ and melanoma with ∼10 mm depth revealing high levels of P-cadherin at sites of KC–MC contacts. Bar, 10 µm. Data are representative of at least three independent experiments. (D) P-cadherin immunostainings of human normal skin and melanoma tissue. Bar, 20 µm. Data are representative of at least three independent experiments. (E) Quantification of anti–P-cadherin immunoreactivity in melanoma patients in KC–MC contacts of normal skin epidermis (n = 9 tissues from different donors), melanoma in situ (n = 9 tissues from different patients), melanoma with tumor depth ∼1 mm (n = 8 tumors from different patients), and ∼10-mm melanoma (n = 4 tumors from different patients). Data are pooled and depicted as mean + SEM. **, P = 0.0054; one-way ANOVA with Tukey posthoc test. cad, cadherin.