UVA Irradiation

Before UVA irradiation, HDFs cells were rinsed and submerged under a thin layer of PBS to prevent UVA absorption by components of the medium, such as VB1. Cells were then irradiated using a Philips UVA lamp with an emission spectrum between 320 and 400 nm. Mock-irradiated cells were manipulated identically, except that they were not exposed to UVA. The dose of UVA irradiation was 10 J/cm² per day, as verified with a UV light meter (Sigma, Shanghai, China) for 3 days. Following each UVA irradiation, cells were incubated in complete medium, supplemented with indicated compounds.