Figure 4. Analysis of principal pathways involved in senescence, apoptosis, and proliferation by western blot. The histogram shows the quantitative evaluation of western blot bands in HDF, HaCaT, and ARPE-19 after UV exposure with two different lamp sources: Purple Dawn (PD) and HVC2654025-16W (HVC) as indicated. The data are expressed as Arbitrary Units (A.U.) with the mean expression values (± SD, n = three). *p < 0.05; **p < 0.01; ***p < 0.001.