The present invention discloses a therapeutic target for the treatment of cystic fibrosis. It was found that inhibition of non-lysosomal glucosylceramidase (GBA2) sufficiently restores chloride current in cells from CF patients carrying the common delF508-CFTR mutation. With the catalytic center (4) of the enzyme positioned on top of the membrane bilayer face particularly potent inhibitors are found in deoxynojirimycin derivatives having a group that is capable of inserting in the membrane bilayer.