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. Author manuscript; available in PMC: 2010 Feb 27.
Published in final edited form as: J Invest Dermatol. 2009 Feb 26;129(7):1805–1815. doi: 10.1038/jid.2008.435

Figure 1. Caffeine augments UVB-induced apoptosis in human keratinocytes.

Figure 1

(a–c) Human keratinocytes were treated with vehicle (medium) or 2 mM of caffeine 30 min prior to 75 mJ/cm2 of UVB irradiation. (a) Western blots using the indicated antibodies. Cells were harvested 8 h after UVB irradiation. (b) Percentage of sub-2N DNA content measured by flow cytometry. Cells were harvested 24 h after UVB irradiation and stained with propidium iodide. (c) Relative cell death was calculated by comparing percentage of sub-2N DNA content in caffeine/UVB-treated cells with that in medium/UVB-treated cells in each experiment. Average of relative cell death is shown (n=4). Error bar, standard error of the mean. (d) Percentage of sub-2N DNA content measured by flow cytometry. Human keratinocytes were treated with caffeine (Caf) or dibutyryl cyclic AMP (db-cAMP) at the indicated doses 30 min prior to 75 mJ/cm2 of UVB irradiation. Cells were harvested 24 h after UVB irradiation and stained with propidium iodide.