JinWoo Bio Co. Ltd. 1 article published in JoVE Biochemistry Quantification of Hypopigmentation Activity In Vitro Yeon-Ji Kim1, Min-Jung Kim1, Dong-Keon Kweon2, Seung-Taik Lim1, Sung-Joon Lee1 1Department of Biotechnology, Graduate School of Life Sciences & Biotechnology, College of Life Sciences and Biotechnology, Korea University, 2JinWoo Bio Co. Ltd We describe three experimental methods for evaluating the hypopigmentation activity of chemicals in vitro: quantification of 1) cellular tyrosinase activity and 2) melanin content, and 3) measurement of melanin by cellular melanin staining and image analysis.