SLC26A9 and cystic fibrosis: However, despite these relevant clues, some open issues and remaining controversies, such as the lack of specific pharmacological modulators, the very low SLC26A9 expression in human airways recently reported by single-cell RNA sequencing (scRNA-Seq) studies, and the sometimes-conflicting reports about its relationships with CFTR and CF phenotype, prevent any conclusive understanding of the potentiality of SLC26A9 as a therapeutic target in CF.