Blocking fatty acid uptake by addition of CD36 inhibitor completely abolished HepG2 cell proliferation induced by culture with PCYT1B-silenced or p53-deficient liver interstitial fluid or hepatocyte-conditioned medium (Supplemental Figure 16, A, H, and I), suggesting the importance of microenvironmental fatty acids in fueling tumor cell proliferation. The gene discussed is TP53; the disease is neoplasm.