Notably, the tetrahydro-γ-carboline 39 did not affect the rescue efficacy of correctors VX-809 or ARN23765 in immortalized bronchial CFBE41o-cells and in primaryHBE cells from an F508del/F508del CF patient and increased by morethan 2-fold the fraction of CFTR-mediated chloride current activatedby submaximal cAMP stimulation in HBE cells from non-CF individuals. Here, CFTR is linked to cystic fibrosis.