The means by which proteins and RNA's are exchanged between cytoplasm and nucleus is of interest to cell biologists. This volume attempts a general review of the growing body of knowledge on the architecture of the nuclear pore-complex, the mechanisms by which transport substrates are sorted, and the supply of energy for exchange processes. The authors challenge the presumptions implicit in some interpretations of the evidence and re-examine the concept of "transport" within cells, suggesting that lessons learned from nucleocytoplasmic transport studies can elucidate wider aspects of cell biology. Standing orders placed before December 31st 1996, will receive a special 10% reduction off the list price of all volumes published within the series between the order date and December 31st, 1997. This offer is valid from June 1996, on a firm order basis only.