2.3. Melanin assay

Melanocytes were lysed by using RIPA lysis buffer (0.1 M Tris-HCl pH 7.2, 1% NP-40, 0.01% SDS and protease-inhibitor cocktail) and centrifuged at 15,000 g for 10 min. The supernatant containing proteins was used in protein quantification with a bicinchoninic acid (BCA) kit (Thermo Fisher Scientific, Waltham, MA, USA), and the pellets containing melanin were dissolved in 1 N NaOH (added with 10% DMSO) and incubated for 30 min at 60°C. Protein and melanin contents were determined by measuring the absorbance at 562 and 450 nm, respectively.