Affiliation: | (1) Imperial Cancer Research Fund, Lincoln's Inn Fields, P.O. Box 123, WC2A 3PX London, UK;(2) Present address: Institute of Child Health, 30 Guilford Street, WC1N 1EH London, UK;(3) Present address: Max-Planck Institut fuer Molekulare Genetik, Ihne Straße 73, 14195 Berlin, Germany |