The purpose of this study is to investigate the effect of two different doses of vitamin D3 (2000 IU vs. 4000 IU) on serum 25-hydroxyvitamin D (25OHD) levels in patients with hepatocellular carcinoma on the liver transplant list. The study will help determine the dose of vitamin D3 that is required for patients with liver cancer to reach a normal level of 25OHD in the blood.