S100A4 and Basement membrane disease: Strutz et al (23) discovered that tubular epithelial cells expressed FSP-1, a cytoskeleton-associated, calcium-binding protein that is normally expressed in fibroblasts, but not in epithelial cells, in a mouse model of anti-tubular basement membrane disease and firstly demonstrated the presence of EMT in renal fibrosis using FSP-1 as a marker.