CFTR and cystic fibrosis: Among the synthesized DNJ derivatives 17–23, only the shortest spacer-containing iminosugar 17 showed an interesting effect regarding the rescue of defective F508del-CFTR function in CF-KM4 cells (however, lower than NBDNJ) [93], as highlighted by both single-cell fluorescence imaging (Figure 7A) and iodide effluxes assay (Figure 7B) [76,81].