FOXM1 and cancer: Interestingly, in addition to the fact that FOXM1-mediated gene expression was suppressed by M1-21, we observed that M1-21 could directly decrease the levels (mRNA or protein) of FOXM1 itself in the cancer cells tested or in spontaneously developed cancer tissues (Fig. S21), probably due to the self-stimulating loop existing in FOXM1-regulated transcription mechanisms of cells [3, 52].