Western blot analysis further revealed that the ratio of VGlut2 to the PF-specific marker vesicular glutamate transporter 1 (VGlut1) (20) dropped from P8 to P15 in WT animals but stayed the same in Pkn1–/– animals (Supplemental Figure 1A; supplemental material available online with this article; https://doi.org/10.1172/JCI96165DS1), further showing imbalances in CF/PF innervation. Here, PKN1 is linked to cystic fibrosis.