RT-PCR indicates that HBE monolayers express SLC26A9 mRNA. (A) RNA harvested from either wt or ΔF508/ΔF508 CF HBE monolayers grown at air liquid interface for at least 2 wk demonstrates endogenous mRNA for both SLC26A9 (1,100-bp product) and CFTR (237-bp product); β-actin was amplified as a control (353-bp product). Apparent differences in SLC26A9 mRNA between wt and CF HBE monolayers were not quantified. (B) HEK 293 cells were transfected with GFP alone (as control), or GFP and SLC26A9 ± wtCFTR, as indicated in Materials and methods and at the bottom of the figure. Control HEK cells do not express endogenous SLC26A9. Molecular weights and markers are the same as in A (n ≥ 3).