PER1 and colorectal cancer: Changes in expression levels of PER1 have been found in some cancers, including pancreatic cancer (Guo et al., 2020), oral squamous cell carcinoma (Yang et al., 2020), endometrial cancer (Wang et al., 2020), colorectal cancer (Holipah and Kuroda, 2020), and non-small-cell carcinoma (Lin et al., 2020), but this has not been studied in OV.