PER2 and renal cell carcinoma: Wu et al. performed differential expression analysis of 14 rhythmic genes in 11 cancers, indicating that most negative regulators such as PER1, PER2, PER3, CRY1, CRY2 and NR1D2, were downregulated in pan-cancers, but they mainly targeted these 11 cancers and did not dig into the common expression changes and related mechanisms of rhythm genes in pan-RCC (Wu et al., 2019).