Figure 1.

K type human endogenous retrovirus envelope (HERV-K ENV) is expressed in nuclear atypia melanoma cells. Formalin-fixed, paraffin embedded microscopic sections of melanoma (a, c) and nevus (b, d) were analyzed to identify multinuclear cells (a, b) and HERV-K ENV expression. (c, d) Shown is a representative staining pattern. Nuclear atypia with features of multinuclear cells were easily detected (arrows) in melanoma (a, c) but not in nevus (b, d) cells. In melanomas, such cells were positive for HERV-K by immunohistochemistry using a monoclonal HERV-K ENV antibody (Austral Biologicals, San Ramon, CA). Nevus cells did not express HERV-K ENV. (d) Magnification: × 400