Figure 3.

The matricryptic FNIII1H site is not essential for fibronectin-mediated attenuation of PDGF-induced intracellular calcium release. FN-null MEFs were seeded on collagen-coated wells (1.1 × 10⁵ cells/cm²). Four hours after seeding, cells were treated for 20 h with (A,C) the indicated fibronectin (FN) fusion proteins (250 nM) or (B) FN (25 nM). Cells were loaded with Fluo-4, stimulated with 30 ng/mL PDGF, and monitored for changes in fluorescence intensity. In (B), cells were treated with 9D2 mAb (25 μg/mL) or non-immune IgG (25 μg/mL) or an equal volume of PBS, 20 min prior to PDGF treatment. Data are presented as relative change in fluorescence intensity from baseline (ΔF/F₀) and are expressed as mean ± SEM of 3 (A,C) or 6 (B) experiments performed in quadruplicate. Values were normalized to the “+GST” condition (A,C) or the “+PBS” condition (B), which was set to 1. * Significantly different versus +GST (A,C) or +PBS (B) by ANOVA (p < 0.05).