HSP90AB1 and leukemia: This implies that progression to advanced disease is associated with a distinct transduction pathways profile at the CD34+ progenitor level, where an imbalance between proliferation and apoptosis has already been described.6 In line with this observation, we also show that when patients could be retested at the time of transformation into overt leukemia, the expression of HSP90 and signaling molecules was significantly increased.