homolog of anaplastic lymphoma kinase (dAlk), encoding a receptor tyrosine kinase in the insulin receptor superfamily, was a member of this cluster (Figure 1A). dAlk expression was decreased by 14% in BxJ flies and increased by 26% in EP1306 flies. We did not observe any changes in the expression of the dAlk ligand Jeb in the dLmo mutant flies, suggesting a specific effect on dAlk expression and not other members of this pathway (data not shown). To confirm the microarray results, we examined dAlk expression using quantitative real-time PCR (qPCR) in EP1306 and BxJ flies. dAlk expression was increased by 18% in the EP1306 flies, consistent with the microarray results (Figure 1B). However, we were unable to recapitulate the small decrease in dAlk expression in BxJ flies observed in the microarray study (data not shown). It is possible that levels of dLMO are sufficiently high such that an additional increase in the BxJ mutants would not significantly affect dAlk expression. ALK protein levels were also increased by 20% in the heads of EP1306 flies when examined by western blotting (Figure 1C), indicating that ALK protein levels changed with a similar magnitude as the transcript in the EP1306 mutant. We next
