Phenotypic characterization by flow cytometry of A549 cells compared to freshly-isolated AECII in resting conditions. A549 cell line and fresh isolated AECII were cultured until confluence and stained with the indicated surface antibodies for phenotypic analysis by flow cytometry. Each experimental condition (seven for A549 cell line and five for AECII) was performed in triplicate, the mean value being represented by a dot. Medians are represented as horizontal bars. A value of P <0.05 was considered to be significant. ** P < 0.01.