FIG. 3.

A single DNase I-protected sequence is detected within the 695-bp SpeI-EcoRI inhibitory fragment. A top-strand-labeled probe corresponding to the 695-bp inhibitory element-containing SpeI-EcoRI MCP-1 5′ fragment was used in DNase I footprinting assays. Nuclear protein extracts for these assays were prepared from two groups of quiescent fibroblasts (lanes Q) and fibroblasts treated with 30 ng of the B-B isoform of PDGF per ml for 2 h (lanes B). Lanes 0 contained no protein, and lane G+A contained the purine sequence of the top-strand-labeled probe. The nucleotide sequence of the overall protected region is given on the right. The arrow highlights a DNase I-hypersensitive site separating the 5′ and 3′ protected subregions. The 12-nt (m1) and 8-nt (m2) sequences mutated in this study are highlighted by the bars on the right.