Scl cis -regulatory elements. The genomic locus of the murine Scl gene and adjacent genes are drawn schematically in the top panel (boxes represent exons and arrowheads indicate gene orientation). The middle diagram shows a Vista plot illustrating sequence conservation between the mouse and human Scl locus. Functional Scl cis-regulatory elements are highlighted in red. Bottom panels show whole mount LacZ staining of embryonic day 12.5 transgenic embryos and relevant histological sections for each individual Scl cis-regulatory element. The -4 Scl and +18/19 Scl enhancers target endothelium and haematopoietic progenitors; promoter 1a and the +23 Scl enhancer target ventral midbrain; promoter 1b targets hind brain and spinal cord, and the +40 Scl enhancer targets midbrain and erythroid cells [18–21, 23–25].