In the presence of cycloheximide, CXCR4 and PAX3 are still inducible, supporting the hypothesis that these genes are direct transcriptional targets of PAX3-FKHR.     ///    These findings of genes regulated by PAX3-FKHR will direct future biological and clinical investigation to important pathways contributing to ARMS tumorigenesis and progression..     ///    This inducible system permits short-term evaluation of downstream expression targets of PAX3-FKHR and complements a panel of stable long-term RD subclones constitutively expressing PAX3-FKHR.     ///    "Using these two sets of resources, we investigated several candidate PAX3-FKHR target genes. "    ///    "First, we demonstrated in both short-term and long-term systems that PAX3-FKHR upregulates expression of the gene encoding the chemokine receptor CXCR4. "    ///    "In addition, we found that expression of wild-type PAX3 is upregulated, whereas expression of wild-type PAX7 is downregulated by PAX3-FKHR. "    ///    "To explore molecular pathways altered by this oncoprotein, we generated an inducible form by fusing PAX3-FKHR to a modified estrogen receptor ligand-binding domain and expressed this construct in the RD embryonal rhabdomyosarcoma cell line. "    ///    "Inducible short-term and stable long-term cell culture systems reveal that the PAX3-FKHR fusion oncoprotein regulates CXCR4, PAX3, and PAX7 expression.. "