The differential nicotinic activation of Hmgcr promoters may be mediated by altered interaction of the c-Fos/n-Myc motifs in cis with c-Fos and n-Myc in trans since these BPH- and BPL- promoter motifs have different binding affinities with these nuclear proteins (Fig. 2 and 10). Here, FOS is linked to benign prostatic hyperplasia.