CFTR and cystic fibrosis: More than 2000 mutations in the CFTR gene have been recorded (http://www.genet.sickkids.on.ca); however, the most common mutation associated with CF is a deletion of a phenylalanine in position 508 (F508delCFTR) which determines a misfolded protein that, although partially functional and sensible to cAMP/PKA-dependent regulation, is unable to reach the plasmatic membrane for its rapid degradation in the endoplasmic reticulum.