U0126, a mitogen-activated protein kinase kinase 1 and 2 (MEK1 and 2) inhibitor, selectively up-regulates main isoforms of CYP3A subfamily via a pregnane X receptor (PXR) in HepG2 cells. - Smutny T; Bitman M; Urban M; Dubecka M; Vrzal R; Dvorak Z; Pavek P (Archives of toxicology, 2014)