Chou Chen-Kung researched the complicated interactions between the hepatitis B virus and the immune system. Through this research, he was able to better understand how the virus could potentially result in liver cancer. By integrating the DNA microarray and gene expression profiles of the two different mouse models (liver regeneration and hepatitis B surface antigen in transgenic mice), Chou was able to spot the differences and similarities in the two models and the possibility of epigenetic regulation.