During the culture of induced pluripotent stem cells (iPSCs or iPS cells) or embryonic stem cells (ESCs or ES cells), human, rat or mouse embryonic fibroblasts are added as a feeder to support long-term undifferentiated culture of these cells. Usually these cells have been treated with mitomycin C (MITC) or irradiated to prevent cell proliferation. For your convience, abm supplies mulitiple different feeder cell lines to satisfy your unique stem cell culture needs.