R elated to Fig. 1 . (A) Ex vivo mucus growth and response to metalloprotease inhibition by EDTA treatment at different ages. Graph show mucus thickness values over time in response to EDTA treatment at t = 30 min (m). (B) Ex vivo mucus growth and response to serine/cysteine protease inhibition by Comp PIC treatment at different ages. Graph shows mucus thickness values over time in response to Comp PIC at t = 30 m. (C) Proteases belonging to different classes detected in mucus proteome data of at least one age group. (D) Volcano plot comparing protease abundance in slow growth (P1–P7) and fast growth (P9–Adult) samples. Proteases color coded by class; data points size proportional to label-free quantification (LFQ) abundance values. Data represent n = 5 (A and B) or n = 3–16 (C and D) animals per group. All error-bar graphs show median and interquartile range. All data are pooled from at least two independent litters or experiments.