Sc 236

The COX-2 selective inhibitor sc-236 (Cayman Chemicals, Ann Arbor, MI, USA) was used to block the enzyme activity. The compound has IC₅₀ of 10 nmol/l and approximately 18,000-fold COX-2 selectivity over COX-1, the other isoform of cyclooxygenase. It was dissolved in DMSO at 20 mmol/l stock, and this stock solution was stored frozen at −20°C.
Bay 11-7085 (Sigma-Aldrich, Gillingham, Dorset, UK) is a specific irreversible inhibitor of TNF-α-mediated IκB phosphorylation with an IC₅₀ ~ 10 μmol/l. It was dissolved in DMSO at 20 mmol/l stock, and this stock solution was stored frozen at −20°C.
The N/TERT-1 keratinocytes and the 3D skin cultures were treated 1 h before irradiation. The inhibitors were kept in the culture medium for the whole duration of the experiment (up to 7 days for the differentiation assay).

ASA or aspirin (acetylsalicylic acid) was purchased from Sigma and diluted in 0.9% NaCl solution with dimethyl sulfoxide (DMSO). The final concentration of DMSO in the medium was 1/1000 (v/v). The solution was freshly prepared. SC-236 was purchased from Cayman Chemical (Ann Arbor, MI, USA) and was dissolved in ethanol with phosphate buffered saline pH 7.6 (PBS) in a 1:4 solution of ethanol:PBS, which was stored at −20°C. Sunitinib Malate was obtained from Pfizer (Pfizer Inc., New York, NY, USA) and was suspended in carboxymethylcellulose (CMC) solution (0.5% CMC, 1.8% NaCl, 0.4% Tween 80, and 0.9% benzyl alcohol in distilled water) for in vivo experiments. Drug aliquots were prepared once weekly and kept in the dark at 4°C. DC101 was obtained from ImClone Systems (Branchburg, NJ, USA) and was diluted in PBS. Aliquots were stored at −20°C. PGE₂ was bought from Cayman Chemical, dissolved in DMSO and stored at −20°C. The Akt inhibitor MK-2206 was purchased from Merck Millipore (Darmstadt, Germany), dissolved in PBS with 20% ethanol and stored at −20°C.