Steel factor and c-kit receptor: from mutants to a growth factor system.

Mutations within the Steel and Dominant Spotting loci of mice have led to the recent identification of a growth factor/receptor system required for the normal development of germ cells, pigment cells and hematopoietic cells. Interactions between the products of these genes, Steel factor and c-Kit respectively, have now been demonstrated to influence various developmental processes, including survival, proliferation, and/or differentiation of cells in a tissue specific manner. In addition, our current understanding of the molecular basis of various Steel and Dominant Spotting alleles coupled with the emerging information on the expression pattern of steel factor and c-kit transcripts during development, is now beginning to explain the pleiotropic affects of these mutations.