When over-expressed, PER1 was shown to set off apoptosis associated with DNA damage and altered expression of critical cell cycle controllers, such as WEE-1, Cyclin B1, and CDC2 in various human breast (MDAMB-231), colon (SW48), lung (NCI-H460), and endometrial (Ishikawa) cancer cell lines [61,62]. Here, WEE1 is linked to cancer.