Apoptosis in A549 cells expressing L101P and R280 mutations. A549 cells were transfected with pEYFP-N1/ABCA3 plasmids and apoptotic markers were analysed by FACS in the transfected (YFP+) population of cells and A549 cells by assaying (A) annexin V+/propidium iodide (PI)- staining, (B) intracellular (i.c.) glutathione (GSH) level through coupling of monochlorobimane with GSH, to determine early apoptosis, and (C) intracellular active caspase 3 level (MFI), to detect late apoptosis. Elevated early and late apoptotic markers were detectable in cells expressing L101P mutation, and one early marker (Annexin V) in cells expressing R280C mutation. Results were calculated from six independent experiments; * p < 0.05, ** p < 0.01, *** p < 0.001.