The murine Bmp4 is under the control of the rat neuron-specific enolase (Eno2) promoter (containing the initial, noncoding exon which increases expression levels). Three lines were established; 1,2, and 3. Levels of Bmp4 mRNA are comparable in all three lines. BMP4 expression is first detectable by Western blot at E16 and the increase persists into adulthood.