Kyowa Hakko Kirin Co., Ltd 1 article published in JoVE Biology Establishment of an Extracellular Acidic pH Culture System Ayano Kondo1, Tsuyoshi Osawa2 1Innovative Technology Laboratories, Kyowa Hakko Kirin Co., Ltd, 2Laboratory for Systems Biology and Medicine, RCAST, The University of Tokyo The acidic tumor microenvironment plays critical roles in tumor progression. To assess the effects of acidic extracellular pH on cancer cells in vitro, we established simple acidic culture systems.