Fig. 2. Immunocytochemical localization of NPC1 in alveolar type II cells. Isolated rat alveolar type II cells were fixed after 24 h in culture, double-labeled with antibodies against ATP-binding cassette A3 (ABCA3; green) and NPC1 (red), and imaged using confocal microscopy. Left: a cluster of 5 individual alveolar epithelial cells, with a single cell (white box) selected for enlargement. Right: single cell panels for ABCA3 (green), NPC1 (red), and ABCA3 and NPC1 (Merge) and merged image with the light micrograph (Merge w/light) show that NPC1 labels the limiting membrane of lamellar bodies (arrows) and small vesicles (arrowheads). A highlighted lamellar body (Merge, box) is enlarged, and projections from a z stack of the top view (x–y), side view (x–z), and axial view (y–z) are shown. Colocalized signal is represented by a yellow color. Scale bar, 5 μm. DOI: (10.1152/ajplung.00383.2011)