[1] Univ Witwatersrand, Johannesburg, South Africa
[2] Univ Cambridge, Cambridge, England
[3] Greys Hosp, Pietermaritzburg, South Africa
[4] Kings Coll London, London, England
[5] Univ York, York, N Yorkshire, England
[6] German Canc Res Ctr, Heidelberg, Germany
[7] Univ New South Wales, Sydney, NSW, Australia
[8] Natl Canc Inst, Bethesda, MD USA
[9] Univ KwaZulu Natal, Durban, South Africa
[10] Univ Cape Town, Cape Town, South Africa
[11] South African Med Res Council, Cape Town, South Africa