The immortalized human corneal epithelial cell line (HCEC) has been previously described.29 (link),30 (link),37 (link) While standard short-tandem repeat (STR)-based validation of this line is not possible due to lack of availability of the original source cells, we do routinely check the cells for the presence of keratin K12 and keratin K3 mRNA by PCR. All cells were grown in Dulbecco's modified Eagle's medium (DMEM; Invitrogen, Carlsbad, CA, USA) supplemented with fetal bovine serum (3%), 1% insulin-transferrin-selinium (ITS; BD Biosciences, Bedford, MA, USA), and 40 μg/mL gentamicin (Life Technologies, Grand Island, NY, USA). Cells were subpassaged using trypsin (Sigma, Ann Arbor, MI, USA) digestion, seeded in 35-mm dishes (Fisher Scientific, Breinigsville, PA, USA), and cultured in a humidified incubator at 37°C with 5% CO2. Culture medium was replaced every 2 days. HCEC and all cultured cells in this study were found to be mycoplasma negative (Mycoplasma Detection Kit; R&D Systems Inc, Minneapolis, MN, USA)