Inhibition of III1-C mediated ERK activation by heparitinase. RASMCs were collected in DMEM+0.5% BSA and were then treated in suspension with either no GAGase ((-), PDGF, FN, C, Hep, and 11C samples) or with 0.1 u/ml of heparitinase (H'ase), or 0.1 u/ml of chondroitinase ABC (C'ase) for 1 hr at 37°C. Cells were then either left in suspension in the absence (-) or presence of PDGF (PDGF) for 10 min, or cells were plated onto dishes precoated with either fibronectin (FN), III1-C (C, Hep, H'ase, and C'ase lanes), or III 11-C (11C). One sample of cells plated onto III1-C contained 100 μg/ml heparin (Hep) in the medium. Cell samples were analyzed by immunoblotting with anti-phospho-p44/42 MAPK antibodies (Phos-ERK panel) followed by anti-ERK antibodies (ERK panel) as described in the legend to Fig. 5. The experiment was performed four times with similar results each time.