Protein X of Hepatitis B virus has diverse cytopathic effects. Specifically, it affects DNA helicase, a basal transcription factor, and DNA repair. This viral protein, while not required for infection has been linked to liver cancer. According to a recent study, protein X interferes with the action of TFIIH, a transcription factor that also takes part in DNA repair. By preventing the repair of DNA in this manner, protein X causes errors to build up. Damage to DNA is not caused by protein X itself, but rather prevents it from being fixed. This finding presents another target for prevention of Hepatitis B related hepatocellular carcinoma. Facilitating DNA repair should counteract liver cancer caused by hepatitis B.