Slides to be stained were air-dried for 20 minutes at room temperature and then fixed for 20 minutes in 100% cold acetone (−20°C). They were washed with phosphate-buffered saline (PBS) 3 times for 5 minutes each time, then incubated for 1 hour in a humidified level chamber in 10% normal donkey serum (D9663; Sigma-Aldrich Corp, St Louis, Missouri) or goat serum (G9023; Sigma-Aldrich Corp) in PBS to block nonspecific staining. Primary antibodies were used at a dilution of 1:100 and incubated overnight at 4°C. The following antibodies were purchased: rabbit polyclonal antibody to gelatinase B (RP3MMP9) (Triple Point Biologics, Forest Grove, Oregon), rabbit polyclonal antibody to transforming growth factor β2 (TGF-β2) (Santa Cruz Biotechnology, Santa Cruz, California); rabbit polyclonal antilaminin (L9393) (Sigma-Aldrich Corp); and mouse monoclonal antibody to mucin 16 (MUC16) and rat monoclonal antibody to β4 integrin (Abcam, Cambridge, Massachusetts). After 3 additional washes with PBS for 5 minutes each, secondary antibodies were applied for 1 hour. The secondary antibodies used were conjugated goat anti–mouse IgG (A-11001), donkey anti–rat IgG (A-21208), and donkey anti–rabbit IgG (A-21206) (Alexa Fluor 488; Invitrogen Molecular Probes, Carlsbad, California). Samples were mounted with the use of mounting medium with 4′,6-diamidino-2-phenylindole (Vectashield; Vector Laboratories, Burlingame, California) for nuclear counterstaining. Negative control sections were processed identically but incubated with strain-specific IgG as the primary antibody. Rabbit IgG, rat IgG, and mouse IgG were purchased (Chemicon, Temecula, California).