A-C Squalene (A), lanosterol (B) and cholesterol (C) abundance in p53+/+ and p53-/- HepG2 cells transfected with control or SQLE siRNA for 48 hours were determined via ultra-high pressure liquid chromatography coupled to mass spectrometry (UHPLC-MS). Protein levels were analyzed by western blotting with specific antibodies (A bottom panel). 