CFTR and cystic fibrosis: Through this strategy, delivering the 5′- and 3′- halves of the cystic fibrosis transmembrane conductance regulator (CFTR) cDNA by two AAV vectors could enable the splicing of two pre-mRNAs, forming a complete and functional CFTR mRNA in human cystic fibrosis airway epithelial IB3-1 cells (Song et al., 2009).