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. Author manuscript; available in PMC: 2016 Apr 1.
Published in final edited form as: J Steroid Biochem Mol Biol. 2015 Jan 21;148:52–63. doi: 10.1016/j.jsbmb.2015.01.014

Figure 2.

Figure 2

Detection of 20S(OH)D3 in human keratinocytes. HaCaT epidermal were incubated with 50 μM vitamin D for 0 (A) or 18 h (B) and extracted for LC/MS analysis. Untreated human epidermis was similarly extracted and analysed (C). The production of 20S(OH)D3 in cultured HaCaT keratinocytes was determined by LC/MS-SIM with m/z = 383 [M+H-H2O]+ (insert in B). The epidermal extract was analysed by LC-MS/MS by ESI with MRM for the transition m/z 401[M+H]+→383[M+H-H2O]+ (C). The arrow shows the retention time corresponding to 20S(OH)D3 standard. The extraction procedures and conditions for LC/MS have been described previously [41].