In APL the TGF-β pathway is deregulated by the cytoplasmic PML isoform (cPML) [26] and we have demonstrated that HF inhibited cell proliferation and induced apoptosis in the APL cell line NB4 through modulation of TGF-β-target genes, such as c-Myc and p21 [1]. This evidence concerns the gene PML and acute promyelocytic leukemia.