Scl-bound regions within TF loci function as enhancers in transgenic mice and display characteristic Scl knockin staining patterns. DNA fragments corresponding to the Scl-bound regions were cloned into a LacZ reporter plasmid and used to generate transgenic F₀ embryos. A Scl LacZ knockin embryo is shown as a reference for the characteristic staining pattern (see text). (Note that the LacZ sequence used to create the Scl knockin mice differs from the one used in transgenic reporters; hence, the more punctuate staining with the knockin.) E11.5 X-Gal–stained whole-mount embryos and paraffin sections of fetal liver are shown. White arrowheads highlight midbrain and fetal liver staining.