Correlation of EFS expression and EFS methylation in 16 UM samples (set I). (A) EFS expression was normalized against HPRT (Hypoxanthine-guanine phosphoribosyl-transferase) expression and given relative to the EFS expression of cultured melanocytes (Mel1 and Mel2). (B) Box plot analysis of EFS expression in 16 UMs grouped according to the EFS methylation state. The difference in EFS expression between unmethylated and fully methylated tumor samples was statistically significant with p = 0.008 (Chi square). Differences between unmethylated and partially methylated tumors as well as between partially methylated and fully methylated tumors were not statistically significant.