(A) Alkyne-tagged reporters of unsaturated fatty acids, alk-16:1, alk-17:1 and alk-18:1 (B) Analysis of lipid droplet induction by Nile red staining. RAW264.7, stimulated for 8 h with LPS/IFN-γ, were treated with DMSO, oleic acid (18:1), alk-16:1, alk-17:1 and alk-18:1 (200 μM) before being fixed with formaldehyde, stained with Nile Red and analyzed by confocal fluorescence microscopy. Cells are present in alk-16 samples, as judged by bright field images, but no Nile Red staining was observed.