SUPPLEMENTAL DATA EXTENDED EXPERIMENTAL PROCEDURES ECM protein enrichment and immunoblotting 100mg of frozen samples were homogenized using a polytron

ECM protein enrichment and immunoblotting 100mg of frozen samples were homogenized using a polytron (Kinematica, Bohemia, NY) in 250μL of buffer C (HEPES pH7.9, MgCl2, KCl, EDTA, Sucrose, Glycerol, Sodium OrthoVanadate) of the CNMCS protein extraction kit. Lysates were then spun for 20 min. at 15,000 rpm at 4°C, the supernatant was saved (intermediate fraction 1, enriched for cytosolic proteins) and the pellet (containing proteins insoluble in buffer C), after a wash, was resuspended in 150μL of buffer N (HEPES pH7.9, MgCl2, NaCl, EDTA, Glycerol, Sodium OrthoVanadate and containing DNase and RNase) and incubated at 4°C for 20 minutes to solubilize nuclear proteins. Protein extract was spun 20 min. at 15,000 rpm at 4°C. The nuclear protein extraction step was repeated twice to allow maximum depletion of nuclear protein from protein extracts. The supernatants (intermediate fraction 2, enriched for nuclear proteins) were pooled and saved and the pellet, resuspended in 100μL of buffer M (HEPES (pH7.9), MgCl2, KCl, EDTA, Sucrose, Glycerol, Sodium deoxycholate, NP-40, Sodium OrthoVanadate), incubated at 4°C for 20 minutes and spun 20 min. at 15,000 rpm at 4°C. The supernatant (intermediate fraction 3, enriched for membrane proteins) was saved and the pellet was finally resuspended in 200μL of buffer CS (Pipes pH6.8, MgCl2, NaCl, EDTA, Sucrose, SDS, Sodium OrthoVanadate), incubated at room temperature for 20 minutes and spun 20 min. at 15,000 rpm. The pellet was finally resuspended in 150μL of buffer C, incubated at 4°C for 20 minutes and spun 20 min. at 15,000 rpm at 4°C. The supernatant from the extraction in buffer CS and from the second extraction in buffer C were pooled (intermediate fraction 4, enriched for cytoskeletal proteins) and saved and the remaining insoluble protein pellet (ECM-enriched fraction) was flash-frozen and kept at -80°C. A 20μL aliquot of total tissue extract and 50μL aliquots of intermediate fractions were mixed with an equal volume of Laemmli Buffer containing 100mM