Expression of Hsap\SMAD4 is governed by UASt regulatory sequences.
When expression is driven by Scer\GAL4ptc-559.1, ectopic vein tissue appears between wing veins L3 and L5. The distance between L3 and L5 appears reduced. Wings are 6% larger than wild type. Ectopic legs have abnormally short and wide tibia that lead to duplicated tarsi on one or more segments. Alternatively, legs may be truncated. When expression is driven by Scer\GAL4A9, wings are enlarged by approximately 16%. Ectopic wing veins also occur.