Raf, a trans-acting locus, regulates the alpha-fetoprotein gene in a cell-autonomous manner.

Genetic analysis provides an approach for identifying regulatory loci that govern the expression of specific genes within the context of the entire organism. Such analyses have defined two unlinked regulatory loci, termed raf and Rif, that modulate the levels of alpha-fetoprotein in liver. Of primary importance for the isolation and characterization of the raf product is to determine whether it is produced by the hepatocyte or whether it is produced by a different cell type. By means of analysis of alpha-fetoprotein expression in livers of embryo aggregation chimeras derived from mice of different raf genotypes it was possible to conclude that the product of the raf locus is expressed as a hepatocyte autonomous function that acts in trans to regulate the level of alpha-fetoprotein messenger RNA.