[1] Inst Canc Res, Chester Beatty Labs, CRC, Biomol Struct Unit, London SW3 6JB, England
[2] Inst Canc Res, CRC, Ctr Canc Therapeut, Sutton SM2 5NG, Surrey, England
[3] Queens Univ Belfast, Sch Chem, Belfast BT9 5AG, Antrim, North Ireland
[4] Univ Reading, Dept Chem, Reading RG6 6AD, Berks, England