Protein kinase C-mediated down-regulation of MDR3 mRNA expression in Chang liver cells11Abbreviations: MDR, multidrug resistance; P-gp, P-glycoprotein; PCR, polymerase chain reaction; PMA, phorbol 12-myristate 13-acetate; 4α-PDD, 4α-phorbol 12,13-didecanoate; and PKC, protein kinase C.