To measure mRNA and protein expression levels of the circadian gene PER2 in HCC tissues and paired paracancerous tissues, we randomly selected liver cancer tissues and paired paracancerous tissues from 30 liver cancer patients from our liver cancer sample library and measured PER2 mRNA expression levels using qRT-PCR (Figures 1A, B), randomly selected liver cancer tissues and paired paracancerous tissues from 54 liver cancer patients. The gene discussed is PER2; the disease is hepatocellular carcinoma.