Fig. 7. Simultaneous analysis of expression, localization and fatty acid uptake. FATP4-(A) or ACSL1 (B)-transfected COS cells were incubated for 2 minutes with 20 µM of the fluorescent fatty acid analog B₁₂-FA, fixed and processed for indirect immunofluorescence. Untransfected cells (outlined, nuclei marked with an asterisk) indicate the background level of fluorescent fatty acid uptake. The distinct reticular ER pattern of FATP4 demonstrates that intracellular localization is sufficient to drive enhanced uptake of fatty acids. Cells expressing ACSL1 localized to mitochondria also show higher B₁₂-FA uptake than untransfected cells. Bar, 10 µm.