TJP1 and cystic fibrosis: Based on this co-localization of CFTR and SLC26A9 with TJ protein ZO-1, we assessed how CFTR and SLC26A9 expression levels vary over the course of differentiation by Western Blot (WB) in primary human nasal epithelial (pHNE) cells derived from an individual with CF homozygous for the F508del mutation and from a non-CF control.