Fig. 2. Gene expression in cultured progenitor cells. (A) Western blots showing liver gene expression in primary cells (Pr) and eighth passage cells (P8), including cell lysates or culture medium. -1 antitrypsin, CK-8 and CK-19 were not expressed in eighth passage cells. Arrowheads indicate monomeric and dimeric forms of orosomucoid. (B) PAI-1 expression with SDS-PAGE showing metabolic labeling with ³⁵S methionine and cysteine (left panel). Compared with HepG2 cancer cells, eight passage progenitor cells showed increased 43 kDa protein expression. Peptide mass spectroscopy suggested that this band was PAI-1, which was verified by western blotting (C), which showed PAI-1 expression in primary and subpassaged progenitor cells but not in HepG2 cells (right panel).