Cell Lines and Cell Culture

The human keratinocyte cell line HaCaT was obtained from the Cell Resource Center at the Institute of Basic Medical Sciences, CAMS/PUMC (Beijing, China). HaCaT cells were maintained in α-MEM supplemented with 10% fetal bovine serum (FBS) under the conditions of 37°C with 5% CO₂. Upon reaching 80% confluent growth, the HaCaT cells were dissociated with 0.05% trypsin-EDTA and resuspended by gentle pipetting in fresh complete media. In addition, 0.05% trypsin-EDTA was purchased from Gibco Laboratories (NY, USA), and the other cell culture regents were purchased from HyClone Laboratories (Logan, UT, USA).