Figure 3.

Pigment epithelium-derived factor (PEDF) is significantly decreased or lost from metastatic melanoma (MM) cells. A–C and G–I: Two representative specimens of metastasis to lymph node (A–C) and to subcutaneous adipose tissue (G–I) exhibit a dramatic loss of PEDF expression. D–F and J–L: Serial sections from the same two specimens show diffuse nuclear and cytoplasmic expression of MITF. M: PEDF immunoreactivity indicates a significant loss of expression in PCMs and MM, compared with CN and melanoma in situ (MIS) by Kruskal–Wallis test (P < 0.0001). Immunoreactivity data are expressed as boxplots; the box includes the first through third quartiles, a plus sign indicates the median, whiskers indicate the minimum and maximum (excluding outliers), and black dots indicate outliers. N: Based on multiple pairwise comparisons, Bonferroni procedure confirmed the boxplot analysis and showed a significant difference in PEDF with same color. Within a color, the diagnostic group with the higher level of PEDF is marked with an asterisk. O: In PCM specimens, tumor thickness was inversely correlated with PEDF expression (P = 0.003). Data are presented as means ± SD. ^∗P < 0.05, ^∗∗P < 0.01, and ^∗∗∗∗P < 0.0001. Scale bars: 50 μm (left column); 25 μm (middle column); 12.5 μm (right column).