Inhibition of III1-C mediated ERK activation by glycosaminoglycans. RASMCs were collected into DMEM + 0.5% BSA and either kept in suspension (-) or cells were seeded onto dishes precoated with 25 μM III1-C (all other lanes). Cells seeded onto III1-C contained either no glycosaminoglycan in the medium (C) or 80 μg/ml heparin (C+Hep), hyaluronic acid (C+HA), heparan sulfate (C+HS), dermatan sulfate (C+DS), chondroitin-4-sulfate (C+C4S), or chondroitin-6-sulfate (C+C6S). After 30 min at 37°C cells were processed and analyzed by immunoblotting with anti-phospho-p44/42 MAPK antibodies (Phos-ERK panel). The blot was subsequently stripped and reprobed with anti-ERK antibodies (ERK panel) as described in the legend to Fig. 5. The experiment was done 3 times with similar results each time.