Transcriptional control by myb oncogene product. 
Structure and function of two domains of c-Myb were analyzed.  We show that a leucine zipper structure is a component of the negative regulatory domain, because its disruption markedly increases both the transactivating and transforming capacities of c-Myb.  Our results suggest that an inhibitor which suppresses transactivation binds to c-Myb through the leucine zipper, and that c-Myb can be oncogenically activated by mis-sense mutation.  We also proposed a model, the "tryptophan cluster", for the structure of the Myb DNA-binding domain, in which the three tryptophans form a cluster in the hydrophobic core in each repeat.  The results of NMR analysis of repeat 3 revealed that the conserved tryptophans play a key role to make the hydrophobic core.