Reagents for lubrication testing materials were as described previously,2 (link),6 (link),33 (link) including hyaluronan (HA) in a 4,000 kDa form (Healon®, Advanced Medical Optics, Santa Ana, CA). The antibody to PRG4 was anti-Lubricin from AbCam (Cambridge, MA);2 (link) nonspecific rabbit IgG was from Pierce (Rockford, IL); mouse anti-rabbit IgG secondary antibody was from Jackson ImmunoResearch (West Grove, PA). Streptomyces hyaluronidase was from Seikagaku (Tokyo, Japan). SeaKem® gold agarose was from Lonza (Rockland, ME); 50X TAE (2M Tris, 0.5M EDTA) electrophoresis buffer was from Life Technologies (Carlsbad, CA); Hybond™-P polyvinylidene difluoride (PVDF) membrane for Western blotting was from GE Healthcare (Piscataway, NJ). Stains-All was from Sigma-Aldrich (St. Louis, MO).