In order to examine the interactions of the cAMP activated CFTR chloride ion channel with other chloride ion channels present in epithelial cells we have generated a model based on antisense mRNA down regulation of CFTR expression. The HT29-derived epithelial cell line CJC4-1 has integrated a plasmid that is constitutively expressing CFTR exons 1-6 in the antisense orientation, from the MoMULV LTR. This cell line shows a reduction in cAMP-activated chloride efflux, as measured by iodide efflux assay, in comparison to the parental HT29 cell line and a sense transfected control.