APOB and Hypercholesterolemia: By regulating low and high density lipoprotein metabolism, RNA editing and the resulting biosynthesis of truncated ApoB48 protein is a critical regulator of plasma cholesterol content (Nakamuta et al., 1996), and dysregulation of APOBEC-1-dependent ApoB48 expression results in hypercholesterolemia and atherosclerosis (Fu et al., 2004; Figure 4).