Additionally, while we have identified the relationship between NTM infection and the observed alterations in cathepsin levels and PKC downregulation within CF airway epithelial cells, we acknowledge that we did not focus on the relationship between cathepsins and PKC and can only speculate on the possible mechanism of PKC regulation by cathepsin as proposed by Kawakibi et al. [46]. Here, CTSS is linked to cystic fibrosis.