The present invention aims to provide a novel undifferentiated state-control agent that maintains and/or improves an undifferentiated state of undifferentiated cells. CCL2 or a protein containing a functional domain thereof is used as the undifferentiated state-control agent. By culturing undifferentiated cells in the presence of the control agent, it is possible to maintain and/or improve an undifferentiated state of the undifferentiated cells. Examples of the undifferentiated cells include embryonic stem cells (ES cells) and induced pluripotent stem cells (iPS cells). The origin of the cells is not particularly limited, and may be a human, mouse, or the like, for example.
REGULATOR OF ANAPLASTIC STATE AND APPLICATIONS THEREFOR