Mutant __SP__ __NODE__ protein ( deletion 337T with its ligand binding domain mutated ) in HepG2 cells is not involved in trans activation of promoter fragment ( 607 26 ) containing a DR + motif from __SP__ __NODE__ gene in HepG2 cells that is increased by 22 ( hydroxycholesterol in culture medium and __SP__ __NODE__ protein in HepG2 cells .