For example, rs885747 and rs2289591 in PER1; rs7602358 in PER2; rs1012477 in PER3; rs1534891 in CSNK1E; rs12315175 in CRY1; rs2292912 in CRY2; rs7950226 in ARNTL; rs11133373 in CLOCK; and rs1369481, rs895521, and rs17024926 in NPAS2 were significantly correlated with prostate cancer susceptibility, while four SNPs, rs885747 and rs2289591 in PER1; and rs1012477 in PER3 and rs11133373 in CLOCK, were more prone to tumor invasion (Zhu et al., 2009). Here, PER1 is linked to prostate cancer.