Phospho-CDC25B (Ser323) Antibody detects endogenous levels of CDC25B only when phosphorylated at Serine 323. CDC25B is a member of the CDC25 family of phosphatases. CDC25B activates the cyclin dependent kinase CDC2 by removing two phosphate groups and it is required for entry into mitosis. CDC25B shuttles between the nucleus and the cytoplasm due to nuclear localization and nuclear export signals.