It is generally acknowledged that cancer stem cells have a strong ability for self-renewal, differentiation, and proliferation.254–256 Therefore, conventional chemotherapy cannot completely eliminate CSCs in cancer cells, and there remain a lot of residues of tumor stem cells after chemotherapy, which is an important reason for drug resistance.257,258 As a critical epigenetic enzyme, LSD1 can further regulate cell resistance by modulating the function of stem cells (Fig. 8). This evidence concerns the gene KDM1A and cancer.