Transcriptional control of lymphoid development: Lessons from gene targeting

Cis-acting control regions have been defined for many hematopoietic genes and used to identify DNA-binding factors. The orderly expression of these factors is hypothesized to control entry into and progression along the various differentiation pathways. Gene-knockout technology is now unveiling the essential functions of these candidate differentiation control factors. Here, Hans Clevers and Rudolf Grosschedl discuss the results and implications of a number of such gene-disruption experiments.