Dulbecco's modified Eagle medium (DMEM), Ham's/F-12 medium, HEPES buffer, fetal bovine serum (FBS), amphotericin B, and gentamicin were purchased from Invitrogen Corporation (Carlsbad, CA). Cholera toxin subunit A, dimethyl sulfoxide (DMSO), hydrocortisone, insulin-transferrin-sodium selenite (ITI) media supplement, human recombinant epidermal growth factor (EGF), mitomycin C, acetone, Triton X-100, BSA, and FITC-conjugated antimouse, -goat, and -rabbit IgGs were obtained from Sigma-Aldrich Corporation (St. Louis, MO). Mounting medium with DAPI was obtained from Vector Laboratories, Inc. (Burlingame, CA). Mouse anti-cytokeratin 10 (K10) was obtained from Chemicon International (Temecula, CA). Goat anti-cytokeratin 12 (K12), mouse anti-cytokeratin 14 (K14), and E-cadherin antibodies were obtained from Santa Cruz Biotechnology (Santa Cruz, CA). Mouse monoclonal anti-p63 (clone 4A4) and Ki67 antibodies, and diaminobenzidine (DAB) were from Dako North America, Inc., (Carpinteria, CA). ABC kits (VECTASTAIN Elite) for mouse, goat, and rabbit IgGs were obtained from Vector Laboratories, Inc. Cell culture inserts were obtained from Corning, Inc. (Corning, NY). A TUNEL apoptosis detection kit was purchased from Promega Corporation (Madison, WI). The NIH 3T3 mouse fibroblasts cell line was obtained from ATCC (Rockville, MD). Optisol-GS corneal storage medium was obtained from Bausch & Lomb, Inc. (Rochester, NY).