Building on our previous studies of BPIFA1 and BPIFB1 in normal lung (Bingle et al. 2005, 2010) and of BPIFA1 in CF tissue (Bingle et al. 2007), the present study investigates the expression of BPIFB1 and BPIFA1 in lungs from CF patients and in bENaC-Tg mice with CF-like lung disease (Mall et al. 2004). Here, BPIFA1 is linked to cystic fibrosis.