C4.4A protein and mRNA expression in nevi, malignant melanoma and metastases. Immunohistochemistry and in situ hybridization was performed for the detection of C4.4A protein and mRNA, respectively, in normal nevi (A–C), superficial spreading melanoma (D–F) and metastases (G–I). Neighboring sections were either processed for immunohistochemical staining using our polyclonal anti-C4.4A antibody (A–C) or in situ hybridization using 35S-labelled 677 base pair nucleotide antisense (D–F) or sense (G–I) probes. Arrows point to the C4.4A-negative melanocytes. Scale (A–C), 25 µm; (D–I), 50 µm.