PER2 and lung cancer: In lung cancer, lysine methyltransferase 2D (KMT2D) is highly expressed and regulates the super enhancers H3K4me1 and H3K27ac of period circadian regulator 2 (PER2; circadian inhibitory factor), affecting the expression of PER2 and its downstream glycolytic genes (Alam et al., 2020).