1. Drug Discovery Division, Southern Research Institute, 2000 Ninth Avenue South, Birmingham, AL 35205, USA
2. Drug Discovery Unit, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
3. Department of Chemical Biology & Therapeutics, St Jude Children's Research Hospital, 262 Danny Thomas Place, Mailstop 1000, Memphis, TN 38105–3678 USA
4. The University of Kentucky College of Pharmacy, 214H BioPharm Complex, Lexington, KY 40536–0596, USA
5. Division of Hematology & Oncology, The University of Alabama at Birmingham, Birmingham, Alabama 35294, USA