A. Human ATII cells were cultured in air-liquid interface (A/L) or plastic (P) in DMEM-based media for five days, as described in materials and methods, and harvested every 24h. B. Expression of surfactant proteins by Western Blot. Cells cultured in A/L expressed higher levels of SP-A, proSP-B, and proSP-C at 96h, and 120h. Cells cultured in P showed a reduction of SP-A and pro-SP-B expression, but no changes in proSP-C. GAPDH was used for normalization. D10: DMEM + 10% FBS; KIA: D10 + KGF + IBMX + 8-Br-cAMP; KIAD: KIA+Dex.