F and G p53+/+ and p53-/- HepG2 cells were cultured for 48 hours in medium containing fetal bovine serum (Serum) or lipoprotein-depleted FBS (LPDS). Protein expression was shown by western blotting (F). mRNA levels of SQLE were examined by qRT-PCR (G). P: premature SREBP2; M: mature SREBP2. 