Matrix fiber organization is increased in FAP
+ matrices. (A) Western analysis showed that FAP was overexpressed in a Tet-inducible fap-transfected NIH-3T3 fibroblast as early as 24 hours following Dox treatment, and its expression maintained for at least 10 days. Parental NIH-3T3 cells and FAP+ fibroblasts in the absence of Dox showed no detectable FAP induction. Recombinant FAP protein (Re-FAP, 92 kD) was used as positive control. (B) Un-extracted matrices were analyzed for the levels of fiber orientation by indirect immunofluorescence using a fibronectin antibody (green) and DAPI (blue). FAP+ fibroblasts produced ECM fibers with enhanced parallel pattern compared to FAP- and FAP+inhibitor matrices. The fiber distribution was determined by calculating the % of fibers arranged in parallel for each acquired region (± 100 of the mode angle). The observed % of fibers was 27%, 45%, and 29% for FAP-, FAP+, and FAP+inhibitor ECMs, respectively.