The secretion of Cl^- by upper airway epithelial cells plays a critical role in maintaining normal airway function. Such secretion is mediated by cystic fibrosis transmembrane conductance regulator (CFTR) and outwardly rectifying Cl^- channels (ORCC). Both of these channels are activated by cAMP and protein kinase A (PKA), and recent work has highlighted the complex nature of this activation process. In 16HBE13o^- cells CFTR forms a complex with the proteins annexin-2/S100A10. Both of these proteins co-precipitate with CFTR, and this interaction is increased on activation of cAMP by forskolin (FSK) and IBMX. Inhibition of PKA or calcineurin prevents the cAMP induced interaction, indicating that they are required for complex formation. This CFTR/annexin-2/S100A10 interaction is also functionally important, as exposure of airway cells to a synthetic acetylated peptide, which disrupts the binding between annexin-2 and S100A10, reduces the magnitude of CFTR currents recorded in whole cell patches. The ORCC currents are also inhibited, indicating that the annexin-2/S100A10 complex plays a critical role in ORCC function too. Nucleoside diphosphate kinase B (NDPK-B) also interacts with CFTR in a cAMP and PKA dependent manner. Exposure to FSK and IBMX increases the interaction of NDPK-B with CFTR, but not the interaction with NDPK-A. Complex formation is disrupted by the synthetic peptide NDPK-B 36-54, and when airway cells are pre-incubated with this peptide (but not NDPK-A 36-54) FSK and IBMX stimulated CFTR and ORCC currents are reduced. These findings highlight the complex nature of the cAMP-dependent regulation of CFTR and ORCC function.