Scatter factor/hepatocyte growth factor (SF/HGF) and its receptor c-Met represent a paracrine signaling system involved in mesenchymal-epithelial interactions during development and during tumor progression. We have examined the promoters of the mouse and human SF/HGF genes by deletion mapping followed by CAT assays as well as by gel retardation and footprinting analysis. The promoter sequences are highly conserved (89.5% identity) up to position -453 from the major transcription start site but diverged considerably further upstream. Both promoters are active in mesenchymal but not epithelial cells thus reflecting the expression pattern of the SF/HGF gene in cells in vitro and in vivo. We have here identified two regulatory sequences in the SF/HGF promoter: a negative element at positions -239 to -258 and a positive element near the major transcription start site; specific deletions destroyed the activities of these elements. We were not able to localize elements on the SF/HGF promoter region that mediate the previously described effects of transforming growth factor beta, 12-O-tetradecanoylphorbol-13-acetate, and coculture of epithelial cells on SF/HGF gene expression. This study represents a first step toward understanding the intricately regulated and cell type-specific expression of the paracrine acting SF/HGF.