19. Which of the following statement for the control of the regulatory transcription factors is NOT correct. (A)Specific synthesis of transcription factors (B)Covalent modifications of protein (such as isoprenylation) (C)Receptor and ligand binding (such as glucocorticoid receptor and its ligand) (D)Availability of functional factor in nucleus (E) Dimerization with active partner (such as Jun and Fos)