Fig. 6. The mitogenic response of OP cells to PDGF requires TN-C. (A) Response of wild-type or TN-C-deficient OP cells to increasing concentrations of the mitogen PDGF (0 to 10 ng/ml) when grown on wild-type or TN-C-deficient astroglia matrix substrates. Results shown represent mean±s.e.m. from at least three independent experiments (WT, wild type; -/-, null; P value was obtained using Student’s t test). Note the lack of response of TN-C-null OP cells to PDGF at all concentrations on the TN-C-null substrate. (B) The lack of proliferative response to PDGF in the absence of TN-C is rescued by the addition of exogenous purified TN-C (10 µg/ml) to the TN-C-null astroglia substrate (Student’s t test: *P<0.05).