Multiple signals are derived from different tissues during wound healing. A comparison of different genes identified by microarray analysis and their expression profiles over time and in relation to U0126-treated samples. (A) Uromodulin (Row 1) is always expressed at the aboral pole and expands expression as a result of injury. Drug treatment appears to block the expansion of expression over time. SoxE1 (Row 2) is expressed in the endoderm around the injury site, appears down-regulated by U0126 and is expressed broadly in the endoderm, and in a potentially salt-and-pepper pattern in cells within the ectoderm of wild-type uninjured individuals. The thiamine enzyme (Row 3) is expressed primarily in the ectoderm of only injured animals. The matrix metalloproteinase (MMP) inhibitor (Row 4) is expressed within the mesenteries as well as the endoderm surrounding the site of injury. Wild-type expression is found throughout the endoderm and is reduced in all U0126-treated samples. The maltase enzyme (Row 5) is also restricted to the mesenteries and endoderm of injured animals. Wild-type expression is lowly expressed in the endoderm, mesenteries and tentacle tips. (B) Removal of U0126 reinitiates gene expression at the site of injury. U0126 was removed after four hours, then animals were allowed to heal for another four hours before fixation. Expression of SoxE1 and Maltase enzyme look strikingly similar to that in animals at four hours in A. All drug-treated samples showed reduced expression. Inset pictures compare control versus drug-treated samples. (Red arrowhead indicates the site of injury).