The promoter methylation level of KLK6 in BLCA was analyzed by UALCAN database, and a significant reduction of KLK6 methylation was observed in BLCA patients (n = 418) compared with normal subjects (Figure 1(i)), which offers a possible explanation of upregulated KLK6 expression in BLCA patients at the epigenetic mechanism. This evidence concerns the gene KLK6 and bladder transitional cell carcinoma.