In human bronchial epithelial cells the cAMP-activated Cl- channel CFTR, plays a critical role in mediating Cl- secretion. This important role is highlighted in cystic fibrosis, where CFTR mutations impact significantly leading to defective muco-cilliary clearance and an increased risk of infection. Previous work has suggested that the fatty acid lubiprostone (Lp) activates CFTR in ovine airway [1]. In the current study the impact of Lp on human bronchial cells (16HBE14o−) was tested. Cells were grown on permeable supports until confluent and a transepithelial resistance of at least 200 Ωcm2 was achieved. Inserts were mounted in an Ussing chamber with standard Krebs (basolateral side) and low Cl- Krebs (apical side). Solutions were bubbled (5% CO2), and all potential and resistance measurements corrected. 10 µA of current was injected to calculate the equivalent short circuit current (ISC). Control measurements were taken for 5 minutes and then 1 µM Lp added apically. At steady-state 10 µM CFTRinh172 was then added to provide an indication of CFTR function. This was repeated in unpaired inserts in the presence of inhibitors for either protein kinase A (protein kinase inhibitor – PKI), adenylate cyclase (SQ22,536) or tyrosine phosphatase (phenylarsine oxide – PAO ). Statistical significance was tested using ANOVAs or Student’s t test as appropriate and assumed at the 5% level. Addition of Lp increased ISC. Under control conditions ISC was 10.1 ± 1.74 µA/cm2 and increased to 26.2 ± 2.63 µA/cm2 with Lp (n=23, mean increase 17.7 ± 2.40 µA/cm2). Addition of CFTRinh172 reversed this increase, a fall of 20.2 ± 2.29 µA/cm2. Pre-incubation with PKI or SQ22,536 prior to the addition of Lp was without effect. The change in ISC with Lp in the presence of both compounds was not significantly different to control: 20.3 ± 2.05 µA/cm2 (n=11) and 18.8 ± 4.77 µA/cm2 (n=8), with PKI and SQ22,536, respectively. The CFTRinh172-sensitive ISC was also unaffected: 14.0 ± 1.10 µA/cm2 (PKI, n=11) and 21.0 ± 4.74 µA/cm2 (SQ22,536n=8). Conversely, pre-incubation with PAO inhibited the response to Lp. The shift in ISC with Lp was 8.58 ± 1.95 µA/cm2 (n=10) approximately half of the observed control response. The CFTRinh172-sensitive ISC was also reduced at 8.86 ± 2.17 µA/cm2 (n=10), again approximately half of the control response. These data indicate that Lp has the ability to activate CFTR in human airway epithelial cells. The action of Lp appears to be independent of cAMP and PKA, the typical CFTR activation pathway, but, given the effect of PAO, appears to involve activation of a tyrosine phosphatase.