A number of these highly hypermethylated candidates, including SOX1 [17–20], WIF1 [21, 22], ACRC [23], ADCY5 [24], BCAP31 [25], NKX6-2 [26], PLK5P [27], and PRSS21 [28], have previously been reported as promoter hypermethylated genes in various cancers (Table 1). Here, PLK5 is linked to cancer.