Immunohistochemistry staining for SB transposase. Shown is immunohistochemistry staining for Sleeping Beauty (SB) transposase in (a) R26-SB11 mice and (b, c) CAGGS-SB10 mice. Anti-transposase immunoreactivity is indicated by brown stain and nuclei are counter-stained blue. In panel (a), essentially all nuclei are positive for transposase in intestine from a R26-SB11 mouse. In panel (b), rare nuclei are positive for transposase in this section of intestine from a CAGGS-SB10 mouse. In panel (c), variegated mesenchymal transposase expression (asterisk) is detected in muscular tissue from the digestive tract of a CAGGS-SB10 mouse.