[1] Univ London Imperial Coll Sci Technol & Med, Dept Chem, London SW7 2AZ, England
[2] Queens Univ Belfast, Ctr Canc Res & Cell Biol, Belfast BT9 7BL, Antrim, North Ireland
[3] Univ Michigan, Dept Med Chem, Ann Arbor, MI 48109 USA
[4] Univ London, Sch Pharm, Canc Res UK Biomol Struct Grp, London WC1N 1AX, England
[5] Univ Michigan, Dept Biol Chem, Dept Chem, Ann Arbor, MI 48109 USA