ap-GFP is expressed in clusters of cells in the somatic mesoderm starting in the abdominal segments in embryonic stage 11. In stage 12 the single lms-positive cell in the abdominal segments is one of the ap-GFP-expressing cells while the cells that begin expression of ap-GFP in the thoracic segments are adjacent to lms-positive cells. Later lms and ap-GFP are both expressed in the lateral transverse muscles and ap-GFP is also expressed in ventral acute muscle. From stage 15, both are expressed in the lateral transverse muscles (LT1-4) in the abdominal segments and in T2 and T3. ap-GFP is not expressed in T1.