Acyl-CoA:cholesterol acyltransferase (ACAT, also known as sterol O-acyltransferase, SOAT) esterifies free cholesterol; previous work demonstrated that pharmacological inhibition of ACAT reduced hepatitis B and C virus replication [41,42], whilst enhancing antiviral and anti-tumour T cell responses [42,43]. This evidence concerns the gene ACAT1 and neoplasm.