Thus, a lower incidence of colon cancer from physical activity has been observed in epidemiological studies.47 In mice an increase of NK cells and NK cell activity from voluntary running was shown to contribute to the suppression of DEN-induced hepatocellular carcinoma (HCC).48 Likewise, in a transgenic model of HCC involving the deletion of PTEN physical activity decreased the number, size and proliferation rate of HCC independently of steatohepatitis.49 The gene discussed is PTEN; the disease is hepatocellular carcinoma.