Paraffin-embedded sections were processed for immunohistochemistry as described previously47 (link). The following primary antibodies were used for immunohistochemistry: αSMA A5228, 1:1000 (Sigma), GR1 MAB1037, 1:750 (R&D); F4/80 Ab6640, 1:100 (Abcam), CD31 sc1506, 1:80 (Santa Cruz Biotechnology), and αvβ6 mAb, 1:25 (human/mouse chimeric 2A1, a kind gift from Dr S. Violette, Biogen Idec, Cambridge, MA). 5 μM sections were stained with picrosirius red or antibody and results quantified using Nikon Elements software. Six random fields from each section were analyzed at a final magnification of 40×. For neutrophil counting, twenty random portal tracts per mouse liver were assessed. For immunofluoresence staining, liver tissue was fixed in 4% paraformaldehyde overnight at 4 °C, immersed in graded sucrose solutions, embedded in OCT (Tissue Tek) and stored at −80 °C. Frozen sections were incubated with the following antibodies: F4/80 MCA497R, 1:100; CD3 MCA500GT, 1:200 (Serotec), CD31 550274, 1:50 (BD Pharmingen), αSMA A5228, 1:200 (Sigma), PDGFRβ, 1:200 (a kind gift from Dr W. Stallcup, Sanford-Burnham Medical Research Institute, La Jolla), phospho-SMAD3 1880-1, 1:100 (Epitomics), cytokeratin WSS Z0622, 1:100 (Dako), αv integrin ab76609, 1:60; desmin ab8592, 1:250 (Abcam) and Alexa Fluor 488-conjugated and Alexa Fluor 555-conjugated secondary antibodies (Invitrogen). Confocal imaging was performed on a Zeiss LSM5 Pascal microscope. Digital morphometric measurements of P-SMAD3 were performed using Image J. Twelve random fields of areas of scar from each section were analyzed at a final magnification of 400×. Digital morphometric measurements of desmin and PDGFRβ immunostaining were performed using Image J. Eight random fields from each section were analyzed at a final magnification of 100×.