The melanoma tissue microarrays were constructed as previously described (30). A total of 232 primary melanomas, 15 local recurrences, and 299 metastatic cores, each measuring 0.6 mm in diameter, were spaced 0.8 mm apart on glass slides. The cohort was constructed from paraffin-embedded, formalin-fixed tissue blocks obtained from the Yale University Department of Pathology Archives. Specimens and clinical information were collected under the guidelines and approval of a Yale University Institutional Review Board. The cohort has been used in prior publications (32). The specimens were resected between 1959 and 2000, with a follow-up range between 2 months and 40 years (mean follow-up time, 6.7 years). Age at diagnosis ranged from 18 to 91 years (mean age, 52.4 years). The cohort included 55% males and 45% females. The time between tumor resection and tissue fixation was not available. A pathologist reviewed slides from all of the blocks to select representative areas of invasive tumor to be cored. The cores were placed on the tissue microarray using a Tissue Microarrayer (Beecher Instruments, Silver Spring, MD). The tissue microarrays were then cut to 0.5-μm sections and placed on glass slides using an adhesive tape-transfer system (Instrumedics, Inc., Hackensack, NJ) with UV cross-linking. Similarly, a tissue microarray was made containing cores from 540 benign nevi. The nevi array contained 31 metastatic specimens from patients that were also represented on the melanoma array. Both arrays contained identical cell lines, cored from pellets as previously described (33). The overlapping metastatic specimens and cell lines were used for normalization of the scores obtained from the benign and malignant arrays.