FIG. 10.

Modulation of the Matn1 promoter activity by cotransfected Nfi proteins. (A to C) AC8Luc was cotransfected with increasing amounts of Nfi expression plasmids without or with a constant amount of SOX9 expression plasmids in the cultures indicated. (C) Western analysis was made with anti-FLAG antibody to determine the relative ratio of Nfib and SOX9 expressed by force at optimal promoter activation. (D) Model for fine-tuning of the promoter activity by the Sox trio and Nfi. Shown are schematics of factor binding to DNA elements during Matn1 activation at the onset of chondrogenesis (a), in early (b) and late proliferative chondroblasts (c) at low and optimal occupancy of sites, respectively, and in the late stage at high occupancy of the Sox (d) or Nfi sites (e). See the text for a detailed description. Symbols are as defined for Fig. 9.