Pre-treatment of CF cultures with signaling inhibitors for 1 h (p38- SB203580, 10 μM; ALK5- SB431542, 10 μM) before the addition of TGF-β prevented the FN stimulation, resulting in FN levels similar to untreated and uninfected controls (Figure 3B). Here, TGFBR1 is linked to cystic fibrosis.