CLDN4 and pulmonary edema: We believe that paclitaxel inhibits the expression of Zo-1 and Claudin-4 and affects TJ integrity, resulting in alveolar-capillary barrier dysfunctions, increased ACM permeability, and exudation of ferrihemoglobin fluid and cells from the capillaries to the alveoli interstitium and even the alveolar cavity, which causes pulmonary edema and, ultimately, ACM thickening and gas diffusion dysfunctions5, 6.