Composition and pro-adhesive activity of A549-CM. (A) Western blotting images of DMEM, three different batches of A549-CM and 1 μg/lane of purified ECM protein (Positive control). Antibodies used recognized: laminin (LM), fibronectin (FN), vitronectin (VT), collagen type IV (Coll IV), collagen type I (Coll I) and thrombospondin (TSP-1). (B) Adhesion of mESCs on increasing percentage of immobilized DMEM (white diamond) and A549-CM (white squares). The data are presented as the percentage of cells adhering to 1 μg/well of immobilized FN, which served as positive control. The adhesion to A549-CM was fitted using four-parameters logistic curve (R2 = 0.9928). The data are mean ± SEM of at least three independent experiments in triplicate.