(H) Senescent nevusmelanocytes (n) stain less intensely for lamin B1 as compared with nonsenescent melanocytes in epidermis (e). White dotted line shows the basement membrane between the dermis and epidermis. Bottom panels (Epi and Nevus) are expanded from white boxed areas on top. Confocal microscopy for DAPI (blue), MelanA (red), and lamin B1 (green) stained tissue. Bars, 20 µm. (I) Quantitation of results from H for three different nevi. Epifluorescence images of lamin B1- and MelanA-stained nevi were obtained and epidermal or nevusMelanA-positive cells were scored for the presence (positive) of a characteristic lamin B1 "ring." At least 50 MelanA-expressing epidermalmelanocytes and at least 100 nevusmelanocytes were scored. Average of three different nevi ± SEM; P < 0.0005. 