CFTR and cystic fibrosis: We targeted the porcine gene encoding CFTR to produce CFTR−/−, CFTRΔF508/ΔF508, and CFTR−/ΔF508 pigs (hereafter referred to as CF pigs).19, 20 Many aspects of human CF are recapitulated in CF pigs including abnormalities of the pancreas, lung, intestine, liver, and other organs.20 Like humans, pigs are born with ethmoid and maxillary sinuses and develop frontal and sphenoid sinuses after birth.21 The CF pig provides a unique opportunity to investigate sinus development and the onset of sinus disease in an animal model from birth.