Examination of the irisin levels in cancer tissues have found increased expression in gastrointestinal [102], breast, ovarian, cervical and endometrial [103], HCC [94] and thyroid [105] cancer tissues and reduced expression in hepatocellular carcinoma [94,95], renal cell carcinoma [104] and NSCLC [80] tissues (Table 4). The gene discussed is FNDC5; the disease is hepatocellular carcinoma.