To further characterize the isoform-specific FGFR responsible for the demonstrated “senolytic” effects, we treated CF ALI cultures with PD173074, a potent and more selective FGFR1 inhibitor (IC50 of 25 nM), at 25 and 50 nM (31, 32). Here, FGFR1 is linked to cystic fibrosis.