CFTR and lung disorder: Of note, a recent study demonstrated that overexpression of human CFTR (hCFTR) failed to ameliorate lung disease in βENaC-Tg mice [34], probably due to different chromosomal integration sites of the transgenic constructs after pronuclear injection leading to expression of hCFTR and βENaC transgenes in different subpopulations of Clara cells [35], or because hCFTR din not function properly in the context of mouse Clara cells [36].