2.1 Cell culture and reagents
Primary human DP cells from passages 2-7 were used in this study (Kwack et al., 2013). The cells were cultured in Dulbecco’s low glucose modified Eagle’s medium (Hyclone, Pittsburgh, PA) supplemented with 10% fetal bovine serum (Gibco, Gaithersburg, MD), 1% antibiotic-antimycotic (Gibco), 1 ng/ml bFGF (Peprotech, Princeton, NJ), and 5 μg/ml insulin (Gibco) at 37℃ in a humidified atmosphere of 5% CO2. A rat vibrissa immortalized DP cell line was donated by the Skin Research Institute of the Amore Pacific Corporation R&D Center (Yongin, Korea). HEK293T cells containing a chromosomally integrated TCF reporter (TOPflash) were cultured in Dulbecco’s Modified Eagle Medium (DMEM) (Gibco) containing 10% (v/v) fetal bovine serum (Gibco) and 100 U/ml penicillin/streptomycin (Gibco) at 37oC in a humidified atmosphere of 5% CO2.