tokens: A candidate DNA sequence with many of the properties predicted for the retinoblastoma susceptibility ( RB1 ) locus has been cloned ( S . H . Friend , R . Bernards , S . Rogelj , R . A . Weinberg , J . M . Rapaport , D . M . Albert , and T . P . Dryja , Nature [ London ] 323 643 - 645 , 1986 ) .