I am culturing mouse embryonic stem cells and using DMEM, 10% FBS. I have added 2.5 ug/ml of amphotericin to the media (final concentration). But my cells were growing slowly and today onwards I can't see cells in my plate. I am doubting that the amphotericin concentration might be high for mouse embryonic stem cells causing decreased proliferation and cell death. Still not sure. Any lead will be helpful. TIA.