Ingomyelin levels, wild-type vs. diseased fibroblasts were incubated overnight with fluorescent BODIPY-FL-C12-sphingomyelin, which fluoresces red (620 nm) at high concentrations and green (530 nm) at physiological concentrations 38, and cells were then fixed. In parallel experiments, in order to track cholesterol levels, cells were fixed and stained with 50 g/mL filipin, which binds to cholesterol