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. Author manuscript; available in PMC: 2012 Jun 11.
Published in final edited form as: Eur J Pharmacol. 2011 Jan 1;660(1):103–110. doi: 10.1016/j.ejphar.2010.11.040

Figure 1.

Figure 1

The melanocyte and the tanning response. Adapted from (Beaumont et al., 2009). Exposure of human skin to ultraviolet radiation results in the release of various factors by keratinocytes and melanocytes. Proopiomelanocortin (POMC) is converted to α-melanocyte stimulating hormone ( MSH), which stimulates melanocortin MC1 receptor (α-MC1R) cAMP signaling in the melanocyte causing the upregulation of genes involved in melanogenesis, ultimately resulting in the tanning response. Agouti signaling protein (ASIP) anatgonises the action of α-MSH. Dotted lines and ? indicate interactions that are in need of further research. ROS, reactive oxygen species; UVR = ultraviolet radiation, HBD3 = human β-defensin 3, END1 = endothelin 1, SCF, stem cell factor; CAT, catalase; bFGF, basic fibroblast growth factor; MITF, microphthalmia transcription factor; DCT, dopachrome tautomerase; USF-1, upstream transcription factor 1.