PPL and cystic fibrosis: Furthermore, mapping of the regulated proteins onto canonical pathway maps revealed that most altered pathways including cytoskeleton remodelling-filaments, regulation of degradation of deltaF508-CFTR in CF and IL-13 signaling via JAK-STAT. Intracellular filaments including epithelial keratins are mainly located in the cytoplasm and nucleus and are cross-linked by binding proteins like plectin, envoplakin, periplakin, epiplakin.