Figure 3.

UVB irradiation and stem cell factor (SCF)/endothelin-1 (ET-1) upregulates guanine deaminase (GDA) expression. (A) GDA mRNA expression was increased in UVB-exposed normal human keratinocytes (NHKs) in a dose-dependent manner at 24 h. (B) Melanin content was significantly increased in the coculture of NHKs and normal human melanocytes (NHMs) when stimulated by 10 ng/mL SCF and 0.1 nM ET-1 for 5 d. (C) GDA and tyrosinase mRNA expression levels were increased by treatment with 10 ng/mL SCF and 0.1 nM ET-1 for 5 d in a coculture of NHKs and NHMs. ** p < 0.01.