Activation of ERK by cell adhesion to III1-C. RASMCs were collected into DMEM + 0.5% BSA and either kept in suspension in the absence (-) or presence of 2 ng/ml PDGF (PDGF), or were seeded onto dishes precoated with either 20 μg/ml FN (FN), 25 μM III1-C (C), or 25 μM III 11-C (11C). Note that the only cells that received growth factor are the cells in the PDGF lane, which received the growth factor 10 min before lysis. After 5, 15, 30, 45 or 60 min at 37°C the cells were lysed in sample buffer and analyzed by inununoblotting with anti-phospho-p44/42 MAPK antibodies (Phos-ERK panel). The blot was then stripped and reprobed with anti-ERK antibodies (ERK panel) to analyze protein loading. This experiment was done more than 3 times with similar results each time.