Hhex-induced promyelocyte transformation is independent of p16^Ink4aand p19^Arf. (A) Growth curves showing expansion of wild-type (WT), Cdkn2a-knockout (p16/19KO), or p19-knockout (p19 KO) Lin⁻ myeloid progenitors, infected with either control (MIG) or Hhex-overexpressing (Hhex) retroviruses and cultured in vitro in the presence of IL-3. (B) FACS analysis of GFP and Mac-1 expression in myeloid cultures as in panel A at day 28 postinfection.