The current in vitro PCLS model revealed several differences to experimental animal models of chronic injury, where during the course of disease, for example in pulmonary fibrosis, a number of AEC I specific proteins are strongly diminished: T1α [48], ICAM-1 [49], aquaporin-5 [50], RAGE [51] and Cav-1 [52]. Here, CAV1 is linked to pulmonary fibrosis.