targeted to the HGF mRNA. Both the control

and the sense-treated explants showed normal histological JapanINTRODUCTION Hepatocyte growth factor (HGF) was originally identified in the serum and platelets of partially hepatectomized rats and was found to be a potent mitogen for normal adult rat hepatocytes in culture (Nakamura et al., 1984; Russell et al., 1984). It was subsequently cloned from both rats and humans (Nakamura et al., 1989). HGF is a heterodimeric molecule composed of a 69 kDa a-subunit and a 34 kDa b-subunit (Nakamura et al., 1986; Gohda et al., 1988), and the molecular cloning of HGF has revealed that it has four kringle domains in the a-chain and a Recently, it has been shown that HGF has a mitogenic effect on various types of epithelial and endothelial cells (Rubin et al., 1991; Nakamura, 1991; Matsumoto et al., 1992) and chon