25(OH)D
3 (BML-DM-100-0001) and 1,25(OH)
2D
3 (BML-DM200-0050) were from Enzo Life Sciences, Inc., Ann Arbor, MI. Stock solutions of 2.5 mM 25(OH)D
3 and 2.4 mM 1,25(OH)
2D
3 were prepared in anhydrous (≥99.5%) ethanol and stored at −80°C. To determine 1,25(OH)
2D
3 in the supernatants we used the 1,25-Dihydroxy Vitamin D EIA kit (AC-62F1) from IDS, Tyne and Wear, UK according to the manufacturer's instructions. Antibodies used included
anti-VDR (D-6) and
anti-CD3ζ (6B10.2) from Santa Cruz Biotechnology, Santa Cruz, CA,
anti-p53 (9282) from Cell Signaling Technology, Danvers, MA, anti-GAPDH from (ab9485) from Abcam, Cambridge, MA and HRP-rabbit anti-mouse Ig (P0260) from DAKO, Glostrup, Denmark. Cycloheximide ready made solution 100 mg/ml in DMSO (
C4859), phorbol 12-myristate 13-acetate (PMA, P8139), ionomycin (I0634), monensin (M5273), leptomycin B (LMB) (L2913) and
ketoconazole (K1003) were from Sigma-Aldrich, St. Louis, MO. A fresh solution of ketoconazole 20 mg/ml in anhydrous ethanol was prepared before each experiment. The proteasome inhibitors lactacystin (426100) and MG-132 (474788) were from Merck Millipore, Nottingham, UK.
Kongsbak M., von Essen M.R., Boding L., Levring T.B., Schjerling P., Lauritsen J.P., Woetmann A., Ødum N., Bonefeld C.M, & Geisler C. (2014). Vitamin D Up-Regulates the Vitamin D Receptor by Protecting It from Proteasomal Degradation in Human CD4+ T Cells. PLoS ONE, 9(5), e96695.