Fig. 6. The effect of Mn²⁺ and immoblized integrin antibodies on the proliferative capacity of OPs on Vn. OPs were plated on Vn (indicated by the horizontal bar) or on immobilized integrin antibodies (β1, β3 and β5), and subsequently left untreated (ctrl, beta 1, beta 3 and beta 5), or treated with either 1 ng/ml PDGF (PDGF), 100 nM PMA (PMA) or 50 µM Mn²⁺ (Mn), and the effect on proliferation was determined as described in Materials and methods. Values shown are means ± SD of at least three independent experiments, each in duplicate. Statistical significance is shown (***P <0.001) between control (ctrl) and the other indicated conditions. Note that integrin activation via Mn²⁺ (in the presence of the ligand Vn) or plating on immobilized integrin β3 antibody (in the absence of ligand) mimicked the mitogenic response of OPs as observed with PDGF-AA or PMA on a Vn substrate.